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In the southeast of European Russia, the gall wasp Aulacidea hieracii (Bouché, 1834) is attacked by ten parasitoid species, including Eupelmus (Eupelmus) microzonus Förster, 1860 and E. (Macroneura) messene Walker, 1839. Although both members of the genus Eupelmus Dalman, 1820 are idiobiont ectoparasitoids, they demonstrate different life-history strategies in respect to many bionomic features. Specifically, E. messene is represented by brachypterous thelytokous females which lay single eggs directly onto the host body. This species can parasitize both concealed and exposed larvae and pupae of A. hieracii, but fails to attack its primary parasitoids. On the contrary, arrhenotokous males and females of E. microzonus are fully winged. These parasitoids usually lay several eggs per host which are placed onto the wall of the host chamber and covered with a particular fibrous substance. E. microzonus never parasitizes pupae or exposed larvae, although it can readily attack concealed larvae of A. hieracii and its primary parasitoids. In addition, hibernating individuals of E. messene undergo obligatory larval diapause, but those of E. microzonus are able to develop without exposure to subzero temperatures. All these data collectively suggest that the former species is highly specialized to exploit A. hieracii as a host, whereas the latter one mostly exhibits the so-called morphotypical specialization. These different strategies allow E. messene and E. microzonus to coexist on the same host species, as a local specialist and a more or less evenly distributed generalist, respectively.

Ecological theory postulates that the niche of co-occurring species must differ along some ecological dimensions in order to allow their stable coexistence. Yet, many biological systems challenge this competitive exclusion principle. For instance, insectivorous bats from the Northern Hemisphere typically form local assemblages of multiple species sharing highly similar functional traits and pertaining to identical feeding guilds. Although their trophic niche can be accessed with unprecedented details using genetic identification of prey, the underlying mechanisms of resource partitioning remain vastly unexplored. Here, we studied the differential diet of three phenotypically and phylogenetically closely-related bat species of the genus Plecotus in an area of sympatry and throughout their entire breeding season (April-October) using DNA metabarcoding. Even at such a small geographic scale, we identified strong seasonal and spatial variation of their trophic niche at both intra- and inter-specific levels. Indeed, while the different bats fed on a distinct array of prey during spring, they showed higher niche overlap during summer and fall, when all three bat species switched their hunting behavior to feed on few temporarily abundant moths. Furthermore, by considering the ecological traits of prey species, we inferred from the menu of each bat species that feeding grounds and hunting techniques differed suggesting that niche partitioning was primarily habitat-driven. As predicted by their phylogenetic relationships, the two most-closely related bat species exhibited the most distinct foraging habitat preferences, while the third, more distantly-related species was more generalist. These results highlight the need of extensive samples to fully understand species coexistence.

Inter‐ and intra‐guild interactions are important in the coexistence of predators and their prey, especially in highly disturbed vegetable cropping systems with sporadic food resources. Assessing the dietary range of a predator taxon characterized by diverse foraging behavior using conventional approaches, such as visual observation and conventional molecular approaches for prey detection, has serious logistical problems. In this study, we assessed the prey compositions and compare the dietary spectrum of a functionally diverge group of predators—spiders—to characterize their trophic interactions and assess biological control potential in Brassica vegetable fields. We used high‐throughput sequencing (HTS) and biotic interaction networks to precisely annotate the predation spectrum and highlight the predator–predator and predator–prey interactions. The prey taxa in the gut of all spider families were mainly enriched with insects (including dipterans, coleopterans, orthopterans, hemipterans, and lepidopterans) with lower proportions of arachnids (such as Araneae) along with a wide range of other prey factions. Despite the generalist foraging behavior of spiders, the community structure analysis and interaction networks highlighted the overrepresentation of particular prey taxa in the gut of each spider family, as well as showing the extent of interfamily predation by spiders. Identifying the diverse trophic niche proportions underpins the importance of spiders as predators of pests in highly disturbed agroecosystems. More specifically, combining HTS with advanced ecological community analysis reveals the preferences and biological control potential of particular spider taxa (such as Salticidae against lepidopterans and Pisauridae against dipterans), and so provides a valuable evidence base for targeted conservation biological control efforts in complex trophic networks., Inter‐ and intra‐guild interactions are important in the coexistence of predators and their prey, especially in highly disturbed vegetable cropping systems with sporadic food resources. In this study, we investigated the trophic interactions of a functionally diverge group of predators—spiders—to accomplish the ultimate goal, that is, the predation of spiders on major crop pests. Despite the generalist foraging behavior of spiders, the community structure analysis and interaction networks highlighted the overrepresentation of particular prey taxa in the gut of each spider family, as well as showed the intrafamily predation between different spiders. Identifying the diverse trophic niche proportions underpins the importance of spiders as predators of pests in highly disturbed agroecosystems.

Background Two coexisting species with similar ecological requirements avoid or reduce competition by changing the extent of their use of a given resource. Numerous coexistence mechanisms have been proposed, but species interactions can also be aggressive; thus, generally a subordinate species modifies its realized niche to limit the probability of direct encounters with the dominant species. We studied niche partitioning between two sympatric wild canids in north-eastern Italy: the golden jackal and the red fox, which, based on competition theories, have a high potential for competition. We considered four main niche dimensions: space, habitat, time, and diet. Results We investigated three study areas monitoring target species populations from March 2017 to November 2018 using non-invasive monitoring techniques. Red fox presence was ascertained in every study area, while golden jackal presence was not ascertained in one study area, where we collected data regarding wolf presence. Considering the two target species, we observed partial diet partitioning based on prey size, with the golden jackal mainly feeding on wild ungulates and the red fox mainly feeding on small mammals. The two canids had an extensive temporal overlap along the diel cycle, having both predominant crepuscular and nocturnal activity patterns, but marked spatial partitioning and differential use of habitats. The golden jackal proved to be specialist concerning the habitat dimension, while the red fox resulted completely generalist: the former selected less human-modified habitats and avoided intensively cultivated lands, while the latter was present in all habitats, including intensively cultivated lands. Conclusions The observed partitioning might be due partially to some ecological adaptations (e.g. specialist vs. generalist use of resources) and specific behaviours (e.g. cooperative vs. solitary hunting) and partially to the avoidance response of the red fox aimed at reducing the probability of direct encounters with the golden jackal.

Sexes often differ more obviously in secondary sexual characteristics than in traits that appear naturally selected, despite conceivable benefits to intersexual niche partitioning. Genetic constraints may play a role in limiting sex‐specific niche evolution; however, it is not clear why this limit should apply to naturally selected traits more than those under sexual selection; the latter routinely produces dimorphism. We ask whether ecological factors and/or features of the mating system limit dimorphism in resource use, or conversely, what conditions are the most permissible ones for sexual niche differences.The scale of mating competition and spatial variation in resource availability can help predict sexually dimorphic niches or the lack thereof. We investigate why and when dimorphism might fail to evolve even if genetic covariation between the sexes posed no constraint.Our analytical model incorporates the first aspect of spatial interactions (scale of mating competition). It is followed by simulations that explore broader conditions, including multiple resources with habitat heterogeneity, genetic correlations and non‐Gaussian resource‐use efficiency functions.We recover earlier known conditions for favourable conditions for the evolution of niche partitioning between sexes, such as narrow individual niche and low degrees of genetic constraint. We also show spatial considerations to alter this picture. Sexual niche divergence occurs more readily when local mating groups are small and different resources occur reliably across habitats. Polygyny (medium‐sized or large mating groups) can diminish the prospects for dimorphism even if no genetic constraints are present. Habitat heterogeneity typically also disfavours niche dimorphism but can also lead to polymorphism within a sex, if it is beneficial to specialize to be very competitive in one habitat, even at a cost to performance in the other.Sexual conflict is usually used to explain dimorphic traits or behaviours. Our models highlight that introducing conflict (achieved by switching from monogamy to polygamy) can also be responsible for sexual monomorphism. Under monogamy, males benefit from specializing to consume other resources than what feeds the female best. Polygyny makes males disregard this female benefit, and both sexes compete for the most profitable resource, leading to overlapping niches., Why is sexual dimorphism driven by intersexual resource competition so rare in nature? The authors use a set of models and simulations to answer the question, and identify conditions favorable for the evolution of such ecological inter‐sexual character displacement, including small spatial scales of interaction and reliable co‐presence of different resources.

Brood parasites such as the common cuckoo Cuculus canorus exploit the parental abilities of their hosts, hosts avoid brood parasitism and predation by showing specific behavior such as loss of feathers, emission of fear screams and contact calls, displaying wriggle behavior to avoid hosts or potential prey, pecking at hosts and prey, and expressing tonic immobility (showing behavior like feigning death or rapid escape from predators and brood parasites). These aspects of escape behavior are consistent for individuals but also among sites, seasons, and years. Escape behavior expressed in response to a broad range of cuckoo hosts and prey are consistently used against capture by humans, but also hosts and brood parasites and predators and their prey. An interspecific comparative phylogenetic analysis of escape behavior by hosts and their brood parasites and prey and their predators revealed evidence of consistent behavior when encountering potential parasites or predators. We hypothesize that personality axes such as those ranging from fearfulness to being bold, and from neophobic to curiosity response in brood parasites constitute important components of defense against brood parasitism that reduces the overall risk of parasitism.

A recent focus in community ecology has been on how within‐species variability shapes interspecific niche partitioning. Primate color vision offers a rich system in which to explore this issue. Most neotropical primates exhibit intraspecific variation in color vision due to allelic variation at the middle‐to‐long‐wavelength opsin gene on the X chromosome. Studies of opsin polymorphisms have typically sampled primates from different sites, limiting the ability to relate this genetic diversity to niche partitioning. We surveyed genetic variation in color vision of five primate species, belonging to all three families of the primate infraorder Platyrrhini, found in the Yasuní Biosphere Reserve in Ecuador. The frugivorous spider monkeys and woolly monkeys (Ateles belzebuth and Lagothrix lagotricha poeppigii, family Atelidae) each had two opsin alleles, and more than 75% of individuals carried the longest‐wavelength (553–556 nm) allele. Among the other species, Saimiri sciureus macrodon (family Cebidae) and Pithecia aequatorialis (family Pitheciidae) had three alleles, while Plecturocebus discolor (family Pitheciidae) had four alleles—the largest number yet identified in a wild population of titi monkeys. For all three non‐atelid species, the middle‐wavelength (545 nm) allele was the most common. Overall, we identified genetic evidence of fourteen different visual phenotypes—seven types of dichromats and seven trichromats—among the five sympatric taxa. The differences we found suggest that interspecific competition among primates may influence intraspecific frequencies of opsin alleles. The diversity we describe invites detailed study of foraging behavior of different vision phenotypes to learn how they may contribute to niche partitioning., Neotropical primates exhibit substantial variation within and between species in color vision abilities; however, little work has explored interspecific variation in a single primate community. In this study, we genotyped functional variation in the middle‐to‐long‐wavelength opsin gene in populations of five sympatric primate species at the Yasuní Biosphere Reserve in Ecuador. We found substantial interspecific and intraspecific variation in color vision across the five species and discuss our findings in the context of dietary specialization and niche partitioning.

Functional traits can determine pairwise species interactions, such as those between plants and pollinators. However, the effects of biogeography and evolutionary history on trait-matching and trait-mediated resource specialization remain poorly understood.We compiled a database of 93 mutualistic hummingbird-plant networks (including 181 hummingbird and 1,256 plant species), complemented by morphological measures of hummingbird bill and floral corolla length. We divided the hummingbirds into their principal clades and used knowledge on hummingbird biogeography to divide the networks into four biogeographical regions: Lowland South America, Andes, North & Central America, and the Caribbean islands. We then tested: (a) whether hummingbird clades and biogeographical regions differ in hummingbird bill length, corolla length of visited flowers and resource specialization, and (b) whether hummingbirds' bill length correlates with the corolla length of their food plants and with their level of resource specialization.Hummingbird clades dominated by long-billed species generally visited longer flowers and were the most exclusive in their resource use. Bill and corolla length and the degree of resource specialization were similar across mainland regions, but the Caribbean islands had shorter flowers and hummingbirds with more generalized interaction niches. Bill and corolla length correlated in all regions and most clades, that is, trait-matching was a recurrent phenomenon in hummingbird-plant associations. In contrast, bill length did not generally mediate resource specialization, as bill length was only weakly correlated with resource specialization within one hummingbird clade (Brilliants) and in the regions of Lowland South America and the Andes in which plants and hummingbirds have a long co-evolutionary history. Supplementary analyses including bill curvature confirmed that bill morphology (length and curvature) does not in general predict resource specialization.These results demonstrate how biogeographical and evolutionary histories can modulate the effects of functional traits on species interactions, and that traits better predict functional groups of interaction partners (i.e. trait-matching) than resource specialization. These findings reveal that functional traits have great potential, but also key limitations, as a tool for developing more mechanistic approaches in community ecology.A free Plain Language Summary can be found within the Supporting Information of this article.

Negative interspecific mating interactions, known as reproductive interference, can hamper species coexistence in a local patch and promote niche partitioning or geographical segregation of closely related species. Conspecific sperm precedence (CSP), which occurs when females that have mated with both conspecific and heterospecific males preferentially use conspecific sperm for fertilization, might contribute to species coexistence by mitigating the costs of interspecific mating and hybridization. We discussed whether two species exhibiting CSP can coexist in a local environment in the presence of reproductive interference. First, using a behaviorally explicit mathematical model, we demonstrated that two species characterized by negative mating interactions are unlikely to coexist because the costs of reproductive interference, such as loss of mating opportunity with conspecific partners, are inevitably incurred when individuals of both species are present. Second, we experimentally examined differences in mating activity and preference in two Harmonia ladybird species known to exhibit CSP. These behavioral differences may lead to local extinction of H. yedoensis because of reproductive interference by H. axyridis. This prediction is consistent with field observations that H. axyridis uses various food sources and habitats whereas H. yedoensis is confined to a less preferred prey item and a pine tree habitat. Finally, by a comparative approach, we observed that niche partitioning or parapatric distribution, but not sympatric coexistence in the same habitat, is maintained between species with CSP belonging to a wide range of taxa, including vertebrates and invertebrates living in aquatic or terrestrial environments. Taken together, it is possible that reproductive interference may destabilize local coexistence even in closely related species that exhibit CSP., We discussed whether two closely related species exhibiting conspecific sperm precedence can coexist in a local environment in the presence of reproductive interference. We used mathematical models, behavioral experiment, and comparative study. We suggested that conspecific sperm precedence does not reduce the overall cost of reproductive interference sufficiently to allow the interacting species to coexist in the same local environment.

†Pycnodontiformes was a successful lineage of primarily marine fishes that broadly diversified during the Mesozoic. They possessed a wide variety of body shapes and were adapted to a broad range of food sources. Two other neopterygian clades possessing similar ecological adaptations in both body morphology (†Dapediiformes) and dentition (Ginglymodi) also occurred in Mesozoic seas. Although these groups occupied the same marine ecosystems, the role that competitive exclusion and niche partitioning played in their ability to survive alongside each other remains unknown. Using geometric morphometrics on both the lower jaw (as constraint for feeding adaptation) and body shape (as constraint for habitat adaptation), we show that while dapediiforms and ginglymodians occupy similar lower jaw morphospace, pycnodontiforms are completely separate. Separation also occurs between the clades in body shape so that competition reduction between pycnodontiforms and the other two clades would have resulted in niche partitioning. Competition within pycnodontiforms seemingly was reduced further by evolving different feeding strategies as shown by disparate jaw shapes that also indicate high levels of plasticity. Acanthomorpha was a teleostean clade that evolved later in the Mesozoic and which has been regarded as implicated in driving the pycnodontiforms to extinction. Although they share similar body shapes, no coeval acanthomorphs had similar jaw shapes or dentitions for dealing with hard prey like pycnodontiforms do and so their success being a factor in pycnodontiform extinction is unlikely. Sea surface temperature and eustatic variations also had no impact on pycnodontiform diversity patterns according to our results. Conversely, the occurrence and number of available reefs and hardgrounds as habitats through time seems to be the main factor in pycnodontiform success. Decline in such habitats during the Late Cretaceous and Palaeogene might have had deleterious consequences for pycnodontiform diversity. Acanthomorphs occupied the niches of pycnodontiforms during the terminal phase of their existence., Pycnodontiform lower jaws and body shape separate from ecologically similar fish clades in a morphospace analysis suggesting minimal competition between these groups. Pycnodontiform diversity appears to be little affected by abiotic factors such as sea level and climate but reef loss may be a more significant factor playing into the success of this clade. Eocene acanthomorph teleosts overlap with pycnodontiforms in body shape but have no overlap in diet so competition between these two groups unlikely factor in the decline of pycnodontiforms.

The seeds of Norway spruce (Picea abies) are important food for the Great Spotted Woodpecker (Dendrocopos major), especially in winter, when other resources are limited. However, little is known about preferences of woodpeckers in terms of the location of anvils, in which seeds of Norway spruce are extracting from cones. In this study, we documented preferences of the Great Spotted Woodpecker for anvil placement sites and checked whether there are differences between males and females in this respect. The research was conducted in primeval oak-lime-hornbeam stands of the Białowieża National Park, E Poland. To determine preferences of woodpeckers regarding the species and condition of trees in terms of the location of anvils in our research we took into consideration available resources of trees. Altogether during our study, we collected data on 358 anvils. They were most often located on large trees, having a much larger trunk diameter than the average diameter of trees from resources. We found the greatest number of anvils on oak (30%), which was also the most preferred tree species by woodpeckers. Anvils were located the most often on branches (72%), on dead parts of trees (67%) and at great heights (on average over 19 m above ground). We found no differences between males and females in the selection of anvil placement sites.

Anthropogenic activities often create distinctive but discontinuously distributed habitat patches with abundant food but high risk of predation. Such sites can be most effectively utilized by individuals with specific behaviors and morphologies. Thus, a widespread species that contains a diversity of sizes and behavioral types may be pre‐adapted to exploiting such hotspots. In eastern Australia, the giant (to >2 m) lizard Varanus varius (lace monitor) utilizes both disturbed (campground) and undisturbed (bushland) habitats. Our surveys of 27 sites show that lizards found in campgrounds tended to be larger and bolder than those in adjacent bushland. This divergence became even more marked after the arrival of a toxic invasive species (the cane toad, Rhinella marina) caused high mortality in larger and bolder lizards. Some of the behavioral divergences between campground and bushland lizards may be secondary consequences of differences in body size, but other habitat‐associated divergences in behavior are due to habituation and/or nonrandom mortality., Lace monitors (Varanus varius) are keen exploiters of anthropogenically disturbed habitat; however, only a subset of morphological and behavioral phenotypes in this species favor these artificial environments (i.e., large, bold individuals). The arrival of a toxic invader (Rhinella marina) may further exacerbate phenotypic divergences.

There is a growing interest on the potential interplay between weather, habitat, and interspecific competition on population dynamics of wild herbivores. Favorable environmental conditions may buffer the negative effects of competition; conversely, competition may be expected to be stronger under harsh environmental conditions. We investigated relationships between competitor abundance, weather, and habitat cover on density and local distribution of a medium‐sized herbivore, the roe deer Capreolus capreolus, as well as its spatial overlap with fallow deer Dama dama in a Mediterranean protected area. Over 11 years (2007–2017), roe deer density was not affected by spring–summer rainfall in the previous year and decreased with increasing density of fallow deer in the previous year. Hence, over the considered temporal scale, results supported a major role of competition over weather in influencing population trends of roe deer. At a finer spatial scale, roe deer occupancy was negatively affected by local abundance of fallow deer, especially in “poorer” habitats. We found a slight support for a positive effect of fallow deer density on interspecific spatial overlap. Moreover, fine‐scale spatial overlap between deer species increased with decreasing rainfall in spring–summer. Fallow deer were introduced to our study area in historical times and their role as superior competitors over roe deer has been found also in other study areas. We suggest a potential role of harsh weather conditions during the growing season of vegetation (i.e. scarce rainfall) in triggering the potential for ecological overlap, emphasizing the negative effects of interspecific competition., We investigated relationships between competitor abundance, weather and habitat on density and distribution of the roe deer Capreolus capreolus, as well as its spatial overlap with fallow deer Dama dama in a Mediterranean protected area. Over 11‐years, roe deer density was not affected by spring‐summer rainfall in the previous year and decreased with increasing density of fallow deer in the previous year. At a finer spatial scale, roe deer occupancy was negatively affected by local abundance of fallow deer, especially in “poorer” habitats; interspecific spatial overlap was influenced both by habitat and rainfall, being negatively related to water precipitation in spring‐summer.

An ecological niche has been defined as an n‐dimensional hypervolume formed by conditions and resources that species need to survive, grow, and reproduce. In practice, such niche dimensions are measurable and describe how species share resources, which has been thought to be a crucial mechanism for coexistence and a major driver of broad biodiversity patterns. Here, we investigate resource partitioning and trophic interactions of three sympatric, phylogenetically related and morphologically similar species of thrushes (Turdus spp.). Based on one year of data collected in southern Brazil, we investigated niche partitioning using three approaches: diet and trophic niche assessed by fecal analysis, diet and niche estimated by stable isotopes in blood and mixing models, and bipartite network analysis derived from direct diet and mixing model outputs. Approaches revealed that the three sympatric thrushes are generalists that feed on similar diets, demonstrating high niche overlap. Fruits from C3 plants were one of the most important food items in their networks, with wide links connecting the three thrush species. Turdus amaurochalinus and T. albicollis had the greatest trophic and isotopic niche overlap, with 90% and 20% overlap, respectively. There was partitioning of key resources between these two species, with a shared preference for fig tree fruits—Ficus cestrifolia (T. amaurochalinus PSIRI% = 11.3 and T. albicollis = 11.5), which was not present in the diet of T. rufiventris. Results added a new approach to the network analysis based on values from the stable isotope mixing models, allowing comparisons between traditional dietary analysis and diet inferred by isotopic mixing models, which reflects food items effectively assimilated in consumer tissues. Both are visualized in bipartite networks and show food‐consumers link strengths. This approach could be useful to other studies using stable isotopes coupled to network analysis, particularly useful in sympatric species with similar niches., Niche dimensions are measurable and describe how species share resources, which has been thought to be a crucial mechanism for coexistence and a major driver of broad biodiversity patterns. Morphologically, similar species of thrushes (Turdus spp.) are generalist species, but distinct, despite overlapping feeding habits allow coexistente.

Made available in DSpace on 2021-06-25T11:05:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-05-22 In tropical forests, the diets of many frugivorous mammals overlap, yet how hyper-diverse assemblages of consumers exploit resources and coexist remains poorly understood. We evaluated competitive interactions among three species of terrestrial frugivorous mammals, the ungulate Tayassu pecari (white-lipped peccary), its close relative Pecari tajacu (collared peccary), and a large rodent (Dasyprocta azarae, agouti), in their exploitation strategies of palm resources of different quality. We conducted the study in a large isolated fragment at the tropical Atlantic Forest of Brazil, where these mammal species show high spatial and temporal overlap. We evaluated if body mass and foraging group size define a hierarchy in exploitation of preferentially richer palm resources. We used camera traps and two-species occupancy models to examine patterns of co-occurrence and variable interaction strength between these consumers and three species of palms. Our analyses supported the hypothesis of partial resource overlap but no competition among frugivores, and a body mass dominance hierarchical exploitation of resources. The larger frugivore (white-lipped peccary) dominated patches of the lipid-rich palm Euterpe edulis, where the smallest frugivore (agouti) was absent. Instead, the smallest frugivore concentrated its foraging in areas with the poorest palm resource, Syagrus oleracea. Collared peccaries preferred areas of high abundance of Syagrus romanzoffiana when the other two mammal species were rarely detected or absent, strongly avoided patches of E. edulis, and showed higher average detection probabilities when agoutis were present. Our study highlights the important role of behavioral plasticity in promoting coexistence and indicates that through context-dependent interactions and hierarchical partitioning of resources, consumers can avoid strong competition, even under conditions of high spatial and temporal overlap and high levels of habitat fragmentation and isolation. Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP) Department of Biology University of Miami Departamento de Ecologia Instituto de Biociências Universidade Estadual Paulista (UNESP)

Mesocarnivores constitute a diverse and often abundant group of species, which are increasingly occupying hweigher trophic levels within multi‐use landscapes. Yet, we know relatively little about their interactions with each other, especially in human‐altered areas. Using camera trap data collected in a forestry concession in the Greater Gorongosa ecosystem of central Mozambique, we examined the spatiotemporal relationships and potential for intraguild competition among three understudied African carnivores: African civets (Civettictis civetta), bushy‐tailed mongooses (Bdeogale crassicauda), and large‐spotted genets (Genetta maculata). After accounting for habitat preferences and tolerance to anthropogenic factors, we found that African civets and bushy‐tailed mongooses avoid each other spatially and temporally. Additionally, civets and mongooses were also both more likely to use sites farther away from human settlements, possibly decreasing the total available habitat for each species if competition is driving this spatial partitioning. In contrast, we did not find evidence for spatial or temporal partitioning between large‐spotted genets and African civets, but bushy‐tailed mongooses altered their activity patterns where they co‐occurred with genets. Our study contributes to scant ecological knowledge of these mesocarnivores and adds to our understanding of community dynamics in human‐altered ecosystems., We examined the spatiotemporal relationships and potential for intraguild competition among three understudied small carnivores: African civets (Civettictis civetta), bushy‐tailed mongoose (Bdeogale crassicauda), and large‐spotted genets (Genetta maculata). We found that civets and mongoose avoid each other, while genets occupied the same, fine‐scale spatial and temporal niches as civets and mongooses. Such interspecific interactions are important to consider for conservation planning because this information allows for better prediction of how trophic networks might shift and function in anthropogenic landscapes, which prevail globally.

A guild is a group of species that have similar requirements of resource and foraging behavior. The knowledge of insectivorous guild could explain foraging patterns, niche exploitation, and competition in a tropical forest. This information could help to monitor the forest by understanding the guild composition and their response to the habitat condition. In order to describe the guild composition and niche overlap of insectivorous birds, we observed all of the individual birds found foraging in the evergreen forest, Baluran National Park. Bray-Curtis similarity index and Pianka niche overlap index were used to analyze the data and grouping the birds into a guild. The cluster analysis consists of 27 bird species revealed 4 guilds: ground gleaner, foliage gleaner, aerial sallier, and bark prober. Based on species richness, foliage gleaner dominates the other groups while bark prober had the least species richness in the evergreen forest. The scarcities of feeding substrate affect guild existence and proved that the diversity of habitat substrate could affect the diversity of guild in an area. Ten congeneric species were found in this habitat and most of them are grouped into foliage gleaner. The junglefowl has the highest niche overlap than any other congeneric species. It seemed that the more specific the foraging substrate niche, the higher the competition among sympatric species. The level of congeneric/sympatric species competition could become the indicator to monitor a specific habitat or forest by understanding their niche partitioning, especially if the species is protected by the law.

Interspecific root separation is an important example of spatial niche differentiation that drives species coexistence in many ecosystems. Particularly under water-stressed conditions, it is believed to be an inevitable outcome of species interactions. However, evidence for and against this idea has been found. So far, studies aiming at reconciling the debate have mainly focused on abiotic determinants. It remains unclear if and to what extent root separation depends on the type and growth form of interacting plants. We conducted a detailed field study in three adjacently located (with pairwise distances

White-nose syndrome (WNS) has caused dramatic declines of several cave-hibernating bat species in North America since 2006, which has increased the activity of non-susceptible species in some geographic areas or during times of night formerly occupied by susceptible species-indicative of disease-mediated competitive release (DMCR). Yet, this pattern has not been evaluated across multiple bat assemblages simultaneously or across multiple years since WNS onset. We evaluated whether WNS altered spatial and temporal niche partitioning in bat assemblages at four locations in the eastern United States using long-term datasets of bat acoustic activity collected before and after WNS arrival. Activity of WNS-susceptible bat species decreased by 79-98% from pre-WNS levels across the four study locations, but only one of our four study sites provided strong evidence supporting the DMCR hypothesis in bats post-WNS. These results suggest that DMCR is likely dependent on the relative difference in activity by susceptible and non-susceptible species groups pre-WNS and the relative decline of susceptible species post-WNS allowing for competitive release, as well as the amount of time that had elapsed post-WNS. Our findings challenge the generality of WNS-mediated competitive release between susceptible and non-susceptible species and further highlight declining activity of some non-susceptible species, especially Lasiurus borealis, across three of four locations in the eastern United States. These results underscore the broader need for conservation efforts to address the multiple potential interacting drivers of bat declines on both WNS-susceptible and non-susceptible species. U.S. Fish and Wildlife Service White-nose Syndrome Grant Program [4500900398]; Fort Drum through the U.S. Army Corps of Engineers' Cooperative Agreement [W9126G-15-2-0005]; Southern Appalachian Cooperative Ecosystems Study Unit Program Published version Funding for this study was provided by the U.S. Fish and Wildlife Service White-nose Syndrome Grant Program Agreement #4500900398 to the U.S. Geological Survey South Carolina Cooperative Fish and Wildlife Research Unit and the Virginia Cooperative Fish and Wildlife Research Unit. Additional support came from Fort Drum through the U.S. Army Corps of Engineers' Cooperative Agreement W9126G-15-2-0005 and the Southern Appalachian Cooperative Ecosystems Study Unit Program to the Virginia Tech Department of Fish and Wildlife Conservation. We thank P. White and the Wisconsin DNR for providing long-term acoustic data from Wisconsin. Fieldwork assistance was provided by L. Coleman, T. Nocera, J. Rodrigue, A. Silvis, and C. Whitman. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. All authors conceived the ideas and designed methodology; Robin Russell, Michael St. Germain, Chris Dobony, Mark Ford, Susan Loeb, and David Jachowski collected the data; Sara Bombaci and Robin Russell analyzed the data; Sara Bombaci and David Jachowski led the writing of the manuscript. All authors contributed critically to the drafts and gave final approval for publication.

We determined the degradation rates of the herbicides 2,4-D and 2,4,5-T by two different bacterial communities. One of these originated from soil heavily contaminated with herbicides from Bien Hoa airbase, the other from the same soil but amended with additional carbon and Gibbs energy sources. The community from the contaminated, but untreated, soil degraded both 2,4-D and 2,4,5-T within 5 days of cultivation. The one from the amended soil, however, hardly showed any degradation of the compounds throughout 23 days of cultivation. After refreshment of the medium and prolonged culturing, however, this community degraded both herbicides within 25 days with progressively increasing rates. nMDS analysis revealed a highly significant differentiation pattern of the two communities. Cultures inoculated with amended soil showed a significant increase of Bacillus and Paenibacillus upon prolonged exposure to the herbicides. The succession in the culture from untreated soil, on the other hand, was dominated by species from the Proteobacteria. We were able to isolate two of them and they were shown to be related to Bordetella petrii and Sphingomonas histidinilytica, successively. Subsequent PCR analyses of their DNA revealed the presence of key genes involved in the degradation of the herbicides. This study provides a more fundamental understanding of the biodegradation of 2,4-D and 2,4,5-T by displaying part of the bacterial community succession during their breakdown allowing a comprehensive view on potential key degraders.

Ecological processes underlying bacterial coexistence in the gut are not well understood. Here, we disentangled the effect of the host and the diet on the coexistence of four closely related Lactobacillus species colonizing the honey bee gut. We serially passaged the four species through gnotobiotic bees and in liquid cultures in the presence of either pollen (bee diet) or simple sugars. Although the four species engaged in negative interactions, they were able to stably coexist, both in vivo and in vitro. However, coexistence was only possible in the presence of pollen, and not in simple sugars, independent of the environment. Using metatranscriptomics and metabolomics, we found that the four species utilize different pollen-derived carbohydrate substrates indicating resource partitioning as the basis of coexistence. Our results show that despite longstanding host association, gut bacterial interactions can be recapitulated in vitro providing insights about bacterial coexistence when combined with in vivo experiments., eLife digest Microbes colonize nearly every environment on Earth, from the ocean and soil to the inner and outer surfaces of animals, such as the gut or skin. They form communities that are usually made up of a diverse range of bacteria, often containing closely related species – a key factor for a successful community. But closely related bacteria can battle for the same resources, so it is unclear how they manage to live alongside each other without competing against one another. While diet is thought to play a key role in enabling closely related bacterial species to co-exist in the gut of an animal, experimental evidence is lacking, due to the difficulty in replicating these systems in the laboratory. One strategy for investigating microbial communities is using honeybees. A major dietary source for honeybees is pollen, which can also be applied in the laboratory to grow diverse types of bacteria found in the honeybee gut. In addition, scientists can generate bees that lack microbial communities in the gut, allowing them to add specific types of bacteria to study their impact. Brochet et al. used this approach with Western honeybees to assess whether diet enables closely related bacteria to live alongside one another in the gut. First, they colonized bees that lacked gut microbes with four closely related bacteria of the genus Lactobacillus, alone or together, and fed the bees either sugar water or sugar water and pollen. After five days, the gut bacteria were analysed. This revealed that bees fed on sugar water only had one dominant Lactobacillus species present in their gut, while bees fed with additional pollen harboured all four Lactobacillus species. Further analysis of these four bacterial species revealed that each of them activates distinct genes when grown on pollen, allowing the different species to consume specific nutrients from broken down pollen. These findings show that closely related bacteria can coexist in the gut by sharing the different nutrients provided in the diet of the host. Consequently, differences in dietary intake in honeybees and other animals may affect the diversity of gut bacteria, and potentially the health of an animal.

19 pages, 6 figures, 3 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2021.673171/full#supplementary-material, Understanding the factors that modulate prokaryotic assemblages and their niche partitioning in marine environments is a longstanding challenge in marine microbial ecology. This study analyzes amplicon sequence variant (ASV) diversity and co-occurrence of prokaryotic (Archaea and Bacteria) communities through coastal-oceanic gradients in the NW Iberian upwelling system and adjacent open-ocean (Atlantic Ocean). Biogeographic patterns were investigated in relation with environmental conditions, mainly focusing on the optical signature of the dissolved organic matter (DOM). Alpha- and beta-diversity were horizontally homogeneous [with the only exception of Archaea (∼1700 m depth), attributed to the influence of Mediterranean water, MW], while beta-diversity was significantly vertically stratified. Prokaryotic communities were structured in four clusters (upper subsurface, lower subsurface, intermediate, and deep clusters). Deep (>2000 m) archaeal and bacterial assemblages, and intermediate (500-2000 m) Bacteria (mainly SAR202 and SAR406), were significantly related to humic-like DOM (FDOM-M), while intermediate Archaea were additionally related to biogeochemical attributes of the high-salinity signature of MW. Lower subsurface (100-500 m) Archaea (particularly one ASV belonging to the genus Candidatus Nitrosopelagicus) were mainly related to the imprint of high-salinity MW, while upper subsurface (≤100 m) archaeal assemblages (particularly some ASVs belonging to Marine Group II) were linked to protein-like DOM (aCDOM254). Conversely, both upper and lower subsurface bacterial assemblages were mainly linked to aCDOM254 (particularly ASVs belonging to Rhodobacteraceae, Cyanobacteria, and Flavobacteriaceae) and nitrite concentration (mainly members of Planctomycetes). Most importantly, our analysis unveiled depth-ecotypes, such as the ASVs MarG.II_1 belonging to the archaeal deep cluster (linked to FDOM-M) and MarG.II_2 belonging to the upper subsurface cluster (related to FDOM-T and aCDOM254). This result strongly suggests DOM-mediated vertical niche differentiation, with further implications for ecosystem functioning. Similarly, positive and negative co-occurrence relationships also suggested niche partitioning (e.g., between the closely related ASVs Thaum._Nit._Nit._Nit._1 and _2) and competitive exclusion (e.g., between Thaum._Nit._Nit._Nit._4 and _5), supporting the finding of non-randomly, vertically structured prokaryotic communities. Overall, differences between Archaea and Bacteria and among closely related ASVs were revealed in their preferential relationship with compositional changes in the DOM pool and environmental forcing. Our results provide new insights on the ecological processes shaping prokaryotic assembly and biogeography, Funding for sampling and analysis was provided by the projects “Fuentes de materia orgánica y diversidad funcional del microplancton en las aguas profundas del Atlántico Norte” (MODUPLAN, Ref. CTM2011-24008-MAR, 2012-2015, Plan Nacional I+D+i), and “Deep Standard Oceanographic Sections monitoring program RADIALES-PRODUNDOS,” funded by the Instituto Español de Oceanografía (IEO). This work was partly funded by European Union Atlantic Area Interreg project iFADO (EAPA/165_2016) and from the Axencia Galega de Innovación (GAIN, Xunta de Galicia, Spain). TR-R was supported by the MICINN program “Personal Técnico de Apoyo a la Investigación” (PTA, Ref. PTA2015-10948-I) and the project iFADO. MN-C was funded by the projects HOTMIX and FERMIO (MINECO, CTM2011–30010–C02 MAR and CTM2014-57334-JIN, respectively), both co-financed with FEDER funds. AA was funded by grant REMEI (CTM2015-70340-R) from the Spanish Ministry of Economy, Industry and Competitiveness, and Grant 2017SGR/1568 from the CIRIT-Generalitat de Catalunya to Consolidated Research Groups, With the institutional support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)

Variation in both inter‐ and intraspecific traits affects community dynamics, yet we know little regarding the relative importance of external environmental filters versus internal biotic interactions that shape the functional space of communities along broad‐scale environmental gradients, such as latitude, elevation, or depth. We examined changes in several key aspects of functional alpha diversity for marine fishes along depth and latitude gradients by quantifying intra‐ and interspecific richness, dispersion, and regularity in functional trait space. We derived eight functional traits related to food acquisition and locomotion and calculated seven complementary indices of functional diversity for 144 species of marine ray‐finned fishes along large‐scale depth (50–1200 m) and latitudinal gradients (29°–51° S) in New Zealand waters. Traits were derived from morphological measurements taken directly from footage obtained using Baited Remote Underwater Stereo‐Video systems and museum specimens. We partitioned functional variation into intra‐ and interspecific components for the first time using a PERMANOVA approach. We also implemented two tree‐based diversity metrics in a functional distance‐based context for the first time: namely, the variance in pairwise functional distance and the variance in nearest neighbor distance. Functional alpha diversity increased with increasing depth and decreased with increasing latitude. More specifically, the dispersion and mean nearest neighbor distances among species in trait space and intraspecific trait variability all increased with depth, whereas functional hypervolume (richness) was stable across depth. In contrast, functional hypervolume, dispersion, and regularity indices all decreased with increasing latitude; however, intraspecific trait variation increased with latitude, suggesting that intraspecific trait variability becomes increasingly important at higher latitudes. These results suggest that competition within and among species are key processes shaping functional multidimensional space for fishes in the deep sea. Increasing morphological dissimilarity with increasing depth may facilitate niche partitioning to promote coexistence, whereas abiotic filtering may be the dominant process structuring communities with increasing latitude., We quantified in situ inter‐specific and intra‐specific variation for deep‐sea fishes, providing novel methodology to partition community‐level trait variation into within and among species components in a multi‐trait context. Increasing morphological dissimilarity with depth may facilitate niche partitioning, promoting coexistence, whereas abiotic filtering may be the dominant process structuring communities across latitude.

Marine sponges have been successful in their expansion across diverse ecological niches around the globe. Pioneering work attributed this success to both a well-developed aquiferous system that allowed for efficient filter feeding on suspended organic matter and the presence of microbial symbionts that can supplement host heterotrophic feeding with photosynthate or dissolved organic carbon. We now know that sponge-microbe interactions are host-specific, highly nuanced, and provide diverse nutritional benefits to the host sponge. Despite these advances in the field, many current hypotheses pertaining to the evolution of these interactions are overly generalized; these over-simplifications limit our understanding of the evolutionary processes shaping these symbioses and how they contribute to the ecological success of sponges on modern coral reefs. To highlight the current state of knowledge in this field, we start with seminal papers and review how contemporary work using higher resolution techniques has both complemented and challenged their early hypotheses. We outline different schools of thought by discussing evidence of symbiont contribution to both host ecological divergence and convergence, nutritional specificity and plasticity, and allopatric and sympatric speciation. Based on this synthesis, we conclude that the evolutionary pressures shaping these interactions are complex, with influences from both external (nutrient limitation and competition) and internal (fitness trade-offs and evolutionary constraints) factors. We outline recent controversies pertaining to these evolutionary pressures and place our current understanding of these interactions into a broader ecological and evolutionary framework. Finally, we propose areas for future research that we believe will lead to important new developments in the field.

1. Predictive species distribution models (SDMs) have become powerful tools to determine habitat use patterns of mobile marine predators and their spatial overlap with potentially impacting anthropogenic activities. 2. This study used SDMs to investigate fine‐scale habitat use patterns of two poorly known and broadly sympatric coastal delphinids, Chilean dolphins (Cephalorhynchus eutropia) and Peale's dolphins (Lagenorhynchus australis), and their spatial interactions with intense aquaculture farming activities in the Chiloé archipelago, southern Chile. 3. A long‐term dataset (2002–2012) of boat‐based dolphin sightings and concurrently in situ collected environmental and anthropogenic variables was analysed using binomial Generalized Additive Models to investigate ecological drivers of each species' fine‐scale distribution and to predict dolphin occurrence spatially. 4. Chilean dolphins preferred shallow (

Identifying the mechanisms that structure niche breadth and overlap between species is important for determining how species interact and assessing their functional role in an ecosystem. Without manipulative experiments, assessing the role of foraging ecology and interspecific competition in structuring diet is challenging. Systems with regular pulses of resources act as a natural experiment to investigate the factors that influence the dietary niches of consumers. We used natural pulses of mast‐fruiting of American beech (Fagus grandifolia) to test whether optimal foraging or competition structure the dietary niche breadth and overlap between two congener rodent species (Peromyscus leucopus and P. maniculatus), both of which are generalist consumers. We reconstructed diets seasonally over a 2‐year period using stable isotope analysis (δ13C, δ15N) of hair and of potential dietary items and measured niche dynamics using standard ellipse area calculated within a Bayesian framework. Changes in niche breadth were generally consistent with predictions of optimal foraging theory, with both species consuming more beechnuts (a high‐quality food resource) and having a narrower niche breadth during masting seasons compared to nonmasting seasons when dietary niches expanded and more fungi (a low‐quality food source) were consumed. In contrast, changes in dietary niche overlap were consistent with competition theory, with higher diet overlap during masting seasons than during nonmasting seasons. Overall, dietary niche dynamics were closely tied to beech masting, underscoring that food availability influences competition. Diet plasticity and niche partitioning between the two Peromyscus species may reflect differences in foraging strategies, thereby reducing competition when food availability is low. Such dietary shifts may have important implications for changes in ecosystem function, including the dispersal of fungal spores., Our study tests the opposing predictions of optimal foraging theory and competition theory for dietary niche breadth and overlap of two closely related and ecologically similar rodent species. We find that the mechanism that structures niche dynamics varies under natural pulses of resource availability with changes in niche breadth consistent with predictions of optimal foraging theory and niche overlap consistent with predictions of competition theory.

Understanding the mechanisms of coexistence between ecologically similar species is an important issue in ecology. Carnivore coexistence may be facilitated by spatial segregation, temporal avoidance, and differential habitat selection. American martens Martes americana and fishers Pekania pennanti are medium-sized mustelids that occur sympatrically across portions of North America, yet mechanisms of coexistence between the two species are not fully understood. We assessed spatial and temporal partitioning in martens and fishers in the Upper Peninsula of Michigan, USA, using camera trap data collected during winter 2013-2015. To investigate spatial segregation, we used a dynamic occupancy model to estimate species' occupancy probabilities and probabilities of persistence and colonization as a function of covariates and yearly occupancy probability for the other species. Temporal segregation was assessed by estimating diel activity overlap between species. We found weak evidence of spatial or temporal niche partitioning of martens and fishers. There was high overlap in forest cover selection, and both marten and fisher occupancy were positively correlated with deciduous forests (excluding aspen [Populus tremuloides]). There was strong temporal overlap ( Δ ^ 4 = 0.81 ; CI = 0.79-0.82) with both species exhibiting largely crepuscular activity patterns. Co-occurrence of martens and fishers appears to be facilitated by mechanisms not investigated in this study, such as partitioning of snow features or diet. Our results add additional insights into resource partitioning of mesocarnivores, but further research is required to enhance our understanding of mechanisms that facilitate marten and fisher coexistence.

Dispersal is an essential process for most animal populations to persist in changing environments. Dispersers are often a nonrandom sample of the population, and differ consistently from nondispersers in a suite of correlated phenotypic traits (“dispersal syndromes”). This phenotypic integration is thought to be adaptive. Here, we investigate whether dispersal tendency of individual pied flycatchers (Ficedula hypoleuca) covaries with a set of repeatable behaviors that should confer advantages for surviving and reproducing in novel environments. We specifically focus on the link between dispersal, foraging behavior, and aggressiveness because selection on foraging tactics or social behaviors likely differs between individuals staying in familiar or dispersing to novel environments. Using repeated measures of nestling provisioning data of pied flycatcher parents in 1 year, we tested if immigrants and philopatric individuals (local recruits and experienced breeders) differed in diet specialization, provisioning rates, levels of aggression, and reproductive success. Results show that individuals differed consistently in their foraging behavior, with immigrants having a more generalist diet and higher feeding rates than philopatric birds, but not in aggressiveness. More generalist males fledged more young. Our findings suggest that prior local knowledge facilitates diet specialization, and that more generalist diets could be adaptive for immigrants breeding in unknown environments. Aggressiveness was not part of the dispersal syndrome in our population, perhaps because high aggression levels are too costly to maintain in high density populations. Understanding the proximate causes and ultimate consequences of variation in dispersal syndromes requires now experimental manipulations of individual dispersal decisions.

Urbanization is influencing patterns of biological evolution in ways that are only beginning to be explored. One potential effect of urbanization is in modifying ecological resource distributions that underlie niche differences and that thus promote and maintain species diversification. Few studies have assessed such modifications, or their potential evolutionary consequences, in the context of ongoing adaptive radiation. We study this effect in Darwin's finches on the Galápagos Islands, by quantifying feeding preferences and diet niche partitioning across sites with different degrees of urbanization. We found higher finch density in urban sites and that feeding preferences and diets at urban sites skew heavily toward human food items. Furthermore, we show that finches at urban sites appear to be accustomed to the presence of people, compared with birds at sites with few people. In addition, we found that human behavior via the tendency to feed birds at non‐urban but tourist sites is likely an important driver of finch preferences for human foods. Site differences in diet and feeding behavior have resulted in larger niche breadth within finch species and wider niche overlap between species at the urban sites. Both factors effectively minimize niche differences that would otherwise facilitate interspecies coexistence. These findings suggest that both human behavior and ongoing urbanization in Galápagos are starting to erode ecological differences that promote and maintain adaptive radiation in Darwin's finches. Smoothing of adaptive landscapes underlying diversification represents a potentially important yet underappreciated consequence of urbanization. Overall, our findings accentuate the fragility of the initial stages of adaptive radiation in Darwin's finches and raise concerns about the fate of the Galápagos ecosystems in the face of increasing urbanization. © 2018 The Authors. Evolutionary Applications published by John Wiley & Sons Ltd This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Interspecific competition can drive niche partitioning along multidimensional axes, including allochrony. Competitor matching will arise where the phenology of sympatric species with similar ecological requirements responds to climate change at different rates such that allochrony is reduced.Our study quantifies the degree of niche segregation in foraging areas and depths that arises from allochrony in sympatric Adélie and chinstrap penguins and explores its resilience to climate change.Three‐dimensional tracking data were sampled during all stages of the breeding season and were used to parameterise a behaviour‐based model that quantified spatial overlap of foraging areas under different scenarios of allochrony.The foraging ranges of the two species were similar within breeding stages, but differences in their foraging ranges between stages, combined with the observed allochrony of 28 days, resulted in them leapfrogging each other through the breeding season such that they were exploiting different foraging locations on the same calendar dates. Allochrony reduced spatial overlap in the peripheral utilisation distribution of the two species by 54.0% over the entire breeding season, compared to a scenario where the two species bred synchronously.Analysis of long‐term phenology data revealed that both species advanced their laying dates in relation to October air temperatures at the same rate, preserving allochrony and niche partitioning. However, if allochrony is reduced by just a single day, the spatial overlap of the core utilisation distribution increased by an average of 2.1% over the entire breeding season.Niche partitioning between the two species by allochrony appears to be resilient to climate change and so competitor matching cannot be implicated in the observed population declines of the two penguin species across the Western Antarctic Peninsula., Reductions in allochrony due to climate change may increase competition among sibling species. The authors investigated this in sympatric Adélie and chinstrap penguins and found that allochrony induced leapfrog foraging, substantially reducing spatial overlap compared to synchronous breeding. However, phenology of both species shifted in parallel, preserving allochrony and niche partitioning.

Made available in DSpace on 2021-06-25T10:27:03Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-03-18 Some prey are exceptionally difficult to digest, and yet even non-specialized animals may consume them—why? Durophagy, the consumption of hard-shelled prey, is thought to require special adaptations for crushing or digesting the hard shells to avoid the many potential costs of this prey type. But many animals lacking specializations nevertheless include hard-bodied prey in their diets. We describe several non-mutually exclusive adaptive mechanisms that could explain such a pattern, and point to optimal foraging and compensatory growth as potentially having widespread importance in explaining costly-prey consumption. We first conducted a literature survey to quantify the regularity with which non-specialized teleost fishes consume hard-shelled prey: stomach-content data from 325 teleost fish species spanning 82 families (57,233 stomach samples) demonstrated that non-specialized species comprise ~75% of the total species exhibiting durophagy, commonly consuming hard-shelled prey at low to moderate levels (~10–40% as much as specialists). We then performed a diet survey to assess the frequency of molluscivory across the native latitudinal range of a small livebearing fish, Gambusia holbrooki, lacking durophagy specializations. Molluscivory was regionally widespread, spanning their entire native latitudinal range (>14° latitude). Third, we tested for a higher frequency of molluscivory under conditions of higher intraspecific resource competition in Bahamian mosquitofish (Gambusia spp.). Examining over 5,300 individuals, we found that molluscivory was more common in populations with higher population density, suggesting that food limitation is important in eliciting molluscivory. Finally, we experimentally tested in G. holbrooki whether molluscivory reduces growth rate and whether compensatory growth follows a period of molluscivory. We found that consumption of hard-shelled gastropods results in significantly reduced growth rate, but compensatory growth following prior snail consumption can quickly mitigate growth costs. Our results suggest that the widespread phenomenon of costly-prey consumption may be partially explained by its relative benefits when few alternative prey options exist, combined with compensatory growth that alleviates temporary costs. Department of Biological Sciences W. M. Keck Center for Behavioral Biology North Carolina State University Department of Biology Appalachian State University Department of Biological Sciences Centre for Ecology Evolution and Behaviour Royal Holloway University of London Instituto de Biociências Universidade Estadual Paulista (UNESP) Department of Applied Ecology North Carolina State University Department of Biology Center for Energy Environment and Sustainability Wake Forest University Instituto de Biociências Universidade Estadual Paulista (UNESP)

Simple Summary Under limited resources, different species may coexist by segregating their food items and foraging time, but neighboring colonies within the same species may have highly overlapping foraging habits. Thus, it is hypothesized that intra-specific competition is more intense than the inter-specific competition. To test this hypothesis, we chose sympatrically breeding Chinstrap and Gentoo penguins at two neighboring colonies and tracked their foraging space and dive depths during chick-rearing. Here we report that there was a larger overlap in the foraging space between the two species than within each species, whereas there was lower inter-specific isotopic niche overlap than intra-specific isotopic niche overlap. Despite the low intra-specific spatial overlap, diets of conspecifics remained similar, resulting in the higher isotopic niche overlaps. Our results suggest that intra-specific competition is higher than inter-specific competition due to a lack of niche partitioning. Abstract Theory predicts that sympatric predators compete for food under conditions of limited resources. Competition would occur even within the same species, between neighboring populations, because of overlapping foraging habits. Thus, neighboring populations of the same species are hypothesized to face strong competition. To test the hypothesis that intra-specific competition is more intense than inter-specific competition owing to a lack of niche partitioning, we estimated the foraging area and diving depths of two colonial seabird species at two neighboring colonies. Using GPS and time-depth recorders, we tracked foraging space use of sympatric breeding Chinstrap and Gentoo penguins at Ardley Island (AI) and Narębski Point (NP) at King George Island, Antarctica. GPS tracks showed that there was a larger overlap in the foraging areas between the two species than within each species. In dive parameters, Gentoo penguins performed deeper and longer dives than Chinstrap penguins at the same colonies. At the colony level, Gentoo penguins from NP undertook deeper and longer dives than those at AI, whereas Chinstrap penguins did not show such intra-specific differences in dives. Stable isotope analysis of δ13C and δ15N isotopes in blood demonstrated both inter- and intra-specific differences. Both species of penguin at AI exhibited higher δ13C and δ15N values than those at NP, and in both locations, Gentoo penguins had higher δ13C and lower δ15N values than Chinstrap penguins. Isotopic niches showed that there were lower inter-specific overlaps than intra-specific overlaps. This suggests that, despite the low intra-specific spatial overlap, diets of conspecifics from different colonies remained more similar, resulting in the higher isotopic niche overlaps. Collectively, our results support the hypothesis that intra-specific competition is higher than inter-specific competition, leading to spatial segregation of the neighboring populations of the same species.

Resource partitioning, the division of limited resources by species to help avoid competition, has been observed in freshwater turtle assemblages in several natural systems but has rarely been studied in tropical African ecosystems. Here, we investigate habitat preferences of two congeneric species in the family Pelomedusidae, Pelusios castaneus and P. cupulatta, in riverine/wetland habitats in the southern Ivory Coast (West Africa). Pelusios castaneus is a widespread species across West-central African savannahs and open forests, whereas P. cupulatta is endemic to the Upper Guinean forest region in West Africa. The two species have a similar diet composition (mainly carnivorous) but diverge considerably in body size, P. cupulatta being much larger. We use hand-fishing-nets and fishing funnel traps to record turtles in 18 distinct sites and analyze habitat preferences by species at two spatial scales. At a macro-habitat scale, P. castaneus is captured mainly in marshlands, whereas P. cupulatta is found in both rivers and wetlands. The two species differ significantly in their use of: (i) banks (P. castaneus being found primarily in spots with grassy banks, whereas P. cupulatta is found in spots with forested banks), and (ii) aquatic vegetation (P. cupulatta prefers spots with more abundant aquatic vegetation than P. castaneus), but both species select sites with no or moderate current. Additionally, in sites where P. cupulatta is not found, P. castaneus expands its spatial niche at multiple habitat scales, notably invading waterbodies with forested banks. Our results suggest that these two Pelomedusid turtle species potentially compete in the freshwater habitats in the southern Ivory Coast.

Simple Summary Predator-prey relationships and competition shape interspecific coexistence in wildlife communities. So far, most published studies have focused on large carnivores and their prey, whereas little is known about medium and small-sized mammal communities. The European brown hare Lepus europaeus is a widespread species in Europe and is part of the diet of many birds of prey and mammalian carnivores of all sizes. Furthermore, competition with other herbivorous mammals at feeding sites has also been suggested. In an area in Central Italy, we have assessed spatiotemporal overlap among brown hare and its potential predators (red fox Vulpes vulpes, pine marten Martes martes, domestic cat Felis catus, and domestic dog Canis familiaris) and a competitor (roe deer Capreolus capreolus). We showed that, outside a fenced area excluding predators and competitors, brown hares become more nocturnal and more active on dark nights to limit encounters with predators, and that they adopt spatial partitioning to avoid competitors, as expected by ecological theory. Abstract Analysis of spatiotemporal partitioning is pivotal to shed light on interspecific coexistence. Most research effort has involved large-sized carnivores and their prey, whereas little attention has been devoted to lagomorphs. We assessed spatiotemporal overlap among the European brown hare Lepus europaeus and its potential competitors and predators through camera-trapping in an area in Central Italy. We estimated the interspecific patterns of the spatiotemporal activity rhythms of brown hares, its potential predators (the red fox Vulpes vulpes, the pine marten Martes martes, the domestic cat Felis catus, and the domestic dog Canis familiaris), and a competitor, the roe deer Capreolus capreolus. Brown hare activity was studied in natural conditions as well as in a fenced area that excluded terrestrial predators and competitors. Free-ranging hares developed a more nocturnal behavior to avoid diurnal predators (i.e., domestic carnivores and martens). Although high temporal overlap was observed between free-ranging brown hares and both red foxes (82%) and roe deer (81%), hares avoided fox by being more active on darkest nights, as well as avoided roe deer through spatial partitioning. We suggest that hares may adapt their spatiotemporal behavior to avoid potential predators and competitors.

International audience; Elephant seals, Mirounga spp., are highly dimorphic, having different energetic requirements according to age and sex, and foraging in various ecological and oceanographic contexts. Resource partitioning has been shown for the sub‐Antarctic populations of southern elephant seals, M. leonina, where colonies are surrounded by narrow shelves that deepen abruptly. In contrast, seals from Península Valdés (Argentina), in the northernmost extent of the breeding range, face an extended, shallow, temperate, and productive continental shelf. We integrated tracking data from 98 animals (juveniles and adults, males and females) gathered over more than two decades, and found that although all available habitats were used, individuals segregated by age and sex. Juvenile males favored shelf habitats, whereas subadult and adult males also used the shelf break. Juvenile females preferred the shelf and the more distant Argentine Basin used by postbreeding and postmolt adult females. Males showed the highest proportion of area‐restricted search locations, suggesting more spatially concentrated feeding activity, and likely reflecting a preference for foraging habitat and prey. Our results are consistent with those from other populations, implying that elephant seals show remarkable similarities in habitat use by age and sex classes, despite broad differences in the offshore habitats between sub‐Antarctic and temperate ecosystems.

Dung beetles use excrement for feeding and reproductive purposes. Although they use a range of dung types, there have been several reports of dung beetles showing a preference for certain feces. However, exactly what determines dung preference in dung beetles remains controversial. In the present study, we investigated differences in dung beetle communities attracted to horse or cow dung from a functional diversity standpoint. Specifically, by examining 18 functional traits, we sought to understand if the dung beetle assembly process is mediated by particular traits in different dung types. Species specific dung preferences were recorded for eight species, two of which prefer horse dung and six of which prefer cow dung. Significant differences were found between the functional traits of the mouthparts of the dung beetles attracted to horse dung and those that were attracted to cow dung. Specifically, zygum development and the percentage of the molar area and the conjunctive area differed between horse and cow dung colonizing beetles. We propose that the quantitative differences in the mouthpart traits of the species attracted to horse and cow dung respectively could be related to the differential capacity of the beetles to filtrate and concentrate small particles from the dung. Hence, the dung preference of dung beetles could be related to their ability to exploit a specific dung type, which varies according to their mouthpart traits. Moreover, we found that larger and nester beetles preferred cow dung, whereas smaller and non-nester beetles preferred horse dung. This finding could be related to the tradeoff between fitness and parental investments, and to the suitability of the trophic resource according to the season and species phenology. Fil: Tonelli, Mattia. Universidad de Alicante; España. Università Degli Studi Di Urbino Carlo Bo; Italia Fil: Gimenez Gomez, Victoria Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú | Universidad Nacional de Misiones. Instituto de Biología Subtropical. Instituto de Biología Subtropical - Nodo Puerto Iguazú; Argentina Fil: Verdú, José R.. Universidad de Alicante; España Fil: Casanoves, Fernando. Centro Agronómico Tropical de Investigación y Enseñanza; Costa Rica Fil: Zunino, Mario. Asti Academic Centre for Advanced Studies; Italia

Introduction Microbial residents of the human oral cavity have long been a major focus of microbiology due to their influence on host health and intriguing patterns of site specificity amidst the lack of dispersal limitation. However, the determinants of niche partitioning in this habitat are yet to be fully understood, especially among taxa that belong to recently discovered branches of microbial life. Results Here, we assemble metagenomes from tongue and dental plaque samples from multiple individuals and reconstruct 790 non-redundant genomes, 43 of which resolve to TM7, a member of the Candidate Phyla Radiation, forming six monophyletic clades that distinctly associate with either plaque or tongue. Both pangenomic and phylogenomic analyses group tongue-specific clades with other host-associated TM7 genomes. In contrast, plaque-specific TM7 group with environmental TM7 genomes. Besides offering deeper insights into the ecology, evolution, and mobilome of cryptic members of the oral microbiome, our study reveals an intriguing resemblance between dental plaque and non-host environments indicated by the TM7 evolution, suggesting that plaque may have served as a stepping stone for environmental microbes to adapt to host environments for some clades of microbes. Additionally, we report that prophages are widespread among oral-associated TM7, while absent from environmental TM7, suggesting that prophages may have played a role in adaptation of TM7 to the host environment. Conclusions Our data illuminate niche partitioning of enigmatic members of the oral cavity, including TM7, SR1, and GN02, and provide genomes for poorly characterized yet prevalent members of this biome, such as uncultivated Flavobacteriaceae.

Exploring natural regeneration facilitates a better understanding of the mechanisms of community assembly and biodiversity formation. However, convincing data on tree regeneration in threatened tropical plant communities are lacking. Dacrydium pectinatum is a constructive and endangered species in tropical montane forests of Hainan Island. This study aims to identify the seedling regeneration patterns of D. pectinatum formation and their key drivers. A total of 204 seedling plots were investigated in the northwest (Bawangling, 90 plots), southwest (Jianfengling, 90 plots) and southeast (Diaoluoshan, 24 plots) of Hainan Island. We examined the variations in the seedling/adult composition, density and richness along local scales and elevation gradients and analyzed the relationships between biotic/abiotic variables and seedling regeneration. The seedling distribution pattern changed with environmental gradients, and the seedling density and richness decreased from low to high latitudes and from low to high elevations. Additionally, the adult density and total base area also showed consistent trends. At the community and species levels, the biotic neighborhood variables had a primary impact on the seedling density and richness. Multiple environmental factors (such as the canopy density, elevation, slope, soil organic matter, and soil total nitrogen) also showed significant correlations with the seedling density and richness. Our study supports conspecific negative density dependence and niche filtering as the general mechanisms of natural regeneration of D. pectinatum formations. Both biotic and abiotic factors might affect the survival and growth of seedlings, and their relative importance varies with environmental gradients and species. We conclude that enclosing forests with moderate stand densities in low-elevation areas to reduce human interference will help optimize the community structure. However, for high-elevation areas and high-density forests, appropriate thinning, manual regeneration and open gaps are needed to improve the light environment and soil nutrients, thereby promoting the natural regeneration of D. pectinatum formations.

The Arctic is warming rapidly, with concomitant sea ice losses and ecosystem changes. The animals most vulnerable to Arctic food web changes are long-lived and slow-growing such as marine mammals, which may not be able to adapt rapidly enough to respond to changes in their resource bases. To determine the current extent and sources of these resource bases, we examined isotopic and trophic niches for marine mammals in the European Arctic using skin carbon (δ13C) and nitrogen (δ 15N) stable isotope (SI) compositions from 10 species: blue, fin, humpback, minke, sperm and white whales, bearded and ringed seals, walruses and polar bears, and dietary fatty acids (FAs) in polar bears, walruses and most of the whale species listed here. SI values showed clear species separation by trophic behaviour and carbon sources. Bearded seals, walruses and white whales had the smallest isotopic niches; these species are all resident High Arctic species and are likely to be particularly vulnerable to changes in Arctic ecosystems. We found clear separation between FA groupings driven by pelagic, benthic and planktonic/algal sources: pelagic FAs in all whales, benthic FAs in walruses, and copepod/algae/ dinoflagellate FAs in polar bears, with some polar bear compositions approaching those of the whales and walruses. There is strong niche partitioning between study species with minimal functional redundancy, which could impact Arctic ecosystem structure and connectivity if populations of these large nutrient vectors are reduced or lost.

Multiple biological control agents have been developed and released to increase control and reduce treatment costs ofPontederia (Eichhornia) crassipesin Florida. Although two species of weevil (Neochetina eichhorniaeandNeochetina bruchi) and the planthopper (Megamelus scutellaris) utiliseP. crassipesfor feeding and reproduction, little is known about their interactions including any negative interactions that might reduce their individual or overall effectiveness in suppressing the plant.Megamelus scutellariswas provided with the choice of weevil-damaged or undamaged plants and allowed to oviposit. Plants were then monitored individually for nymph emergence to determine the plant preference for adults. There were no differences in F(1)emergence numbers among the treatments indicating that in this specific situation the potential for negative interactions betweenNeochetinaspp. andM. scutellarisis minimal. Additional studies are required to quantify the potential for other types of interactions among these biological control agents. Public domain – authored by a U.S. government employee

Maternal environmental effects create lagged population responses to past environments. Although they are ubiquitous and vary in expression across taxa, it remains unclear if and how their presence alters competitive interactions in ecological communities.Here, we use a discrete‐time competition model to simulate how maternal effects alter competitive dynamics in fluctuating and constant environments. Further, we explore how omitting maternal effects alter estimates of known model parameters from observational time series data.Our simulations demonstrate that (i) maternal effects change competitive outcomes, regardless of whether competitors otherwise interact neutrally or exhibit non‐neutral competitive differences, (ii) the consequences of maternal effects for competitive outcomes are mediated by the temporal structure of environmental variation, (iii) even in constant conditions, competitive outcomes are influenced by species' maternal effects strategies, and (iv) in observational time series data, omitting maternal effects reduces variation explained by models and biases parameter estimates, including competition coefficients.Our findings demonstrate that the ecological consequences of maternal effects hinge on the competitive environment. Evolutionary biologists have long recognized that maternal effects can be an important but often overlooked strategy buffering populations from environmental change. We suggest that maternal effects are similarly critical to ecology and call for research into maternal effects as drivers of dynamics in populations and communities., Maternal effects can overturn competitive differences among species, driving patterns of coexistence or exclusion that would not be possible in their absence. Who wins and who loses depend on the particular strategies pairs of species employ, as well as how variable the environment they are found in is. As such, maternal effects may act as a species' niche dimension.

BackgroundPandi’s mushroom-tongue salamander (Bolitoglossa pandi) is one of the threatened amphibians in South America, as well as a flagship species for the Colombian conservation agenda. This species is endemic to the Andean cloud forests of the western slope of the Cordillera Oriental of Colombia, occurring only in the department of Cundinamarca within a narrow elevational range. At night,B. pandican be seen perching on the upper side of leaves at heights ranging from ground level to 2.5 m. During the day, it can be found under leaf litter or cover objects. Few studies have provided relevant information that can help the Colombian government to formulate lines of action for the conservation of this species; consequently, its threat assessments so far have been based on very limited information.MethodsWe conducted surveys for salamanders in four municipalities of Cundinamarca, Colombia, using two approaches: visual encounter surveys (Guaduas and Villeta) and the basic sampling protocol for single-species occupancy modeling (Supatá and Venecia). Multivariate analyses were employed to explore the correlation between habitat structure and natural history traits, abundance, and detection/non-detection ofB. pandi.We evaluated theB. pandiactivity pattern through kernel density curves for each sampling occasion and explored the variability of salamander abundance during their activity period by performing a nested ANOVA.ResultsWe report the discovery of two new populations ofB. pandi,which represent the most northwestern records known. A significant correlation between body length, body mass, and habitat structure was observed. Multivariate analyses indicated that leaf litter depth, mean temperature, percent vegetation cover, and altitude were the habitat variables that together explained 60.3% of theB. pandiabundance variability, as well as the main determinants of its optimal habitat.Bolitoglossa pandiexhibits an activity pattern characterized by two main activity peaks, in which niche time-partitioning was observed. Across the surveyed area, we found a healthy, stable, highly dense population ofB. pandi(>1,300 individuals), with seasonal variability between development stages.DiscussionGiven the high habitat specificity ofB. pandi,the species is highly vulnerable to local changes. Thus, we recommend thatB. pandibe retained as Endangered (EN) on the IUCN Red List, based on the IUCN Criterion B, given its restricted extent of occurrence (ca. 2,500 km2) and the ongoing threats from agriculture, cattle ranching, logging, and urban development, which continue to reduce its suitable habitat.

International audience; Plant disease complexes are a playground to investigate coinfections in natural or cultivated systems. Pathogens of such complexes may affect each other through direct and/or indirect interactions and lead to changes in virulence or aggressiveness, offspring production, and transmission. As coinfections by sympatric host-pathogens can strongly influence pathogen dynamics and their evolutionary trajectories, new insights into the mechanisms of their coexistence is thus of critical importance. In order to characterize differences in ecological niches liable to explain species coexistence on the same host, the inter- and intraspecific diversity of the life history traits in natural collections of the two main pathogens (Peyronellaea (formerly Didymella) pinodes [Dp] and Phoma medicaginis var. pinodella [Pmp]) of the ascochyta blight disease complex of pea was evaluated under controlled conditions. Dp strains developed 1.3 times faster and produced longer, mainly bicellular spores and in lower amounts (3.7 times less) than Pmp strains. Pmp strains were separated into two groups, one producing more pycnidiospores, mainly bicellular, with less resources, and the other with mainly unicellular ones. These three groups can be interpreted as three distinct life history strategies: pioneer colonizer (Dp), scavenger (large-spored Pmp), and intermediate (small-spored Pmp), allowing differentiation in access to and use of resources. While this experimental work provides new insight into coexistence of two species of the ascochyta blight disease complex of pea, it also raises the question of the benefit of having two distinct life history strategies for one species (Pmp).

Microbes are ubiquitous throughout the world's oceans, yet the manner and extent of their influence on the ecology and evolution of large, mobile fauna remains poorly understood. Here, we establish the intestinal microbiome as a hidden, and potentially important, ‘functional trait’ of tropical herbivorous fishes—a group of large consumers critical to coral reef resilience. Using field observations, we demonstrate that five common Caribbean fish species display marked differences in where they feed and what they feed on. However, in addition to space use and feeding behaviour—two commonly measured functional traits—we find that interspecific trait differences are even more pronounced when considering the herbivore intestinal microbiome. Microbiome composition was highly species specific. Phylogenetic comparison of the dominant microbiome members to all known microbial taxa suggest that microbiomes are comprised of putative environmental generalists, animal-associates and fish specialists (resident symbionts), the latter of which mapped onto host phylogeny. These putative symbionts are most similar to—among all known microbes—those that occupy the intestines of ecologically and evolutionarily related herbivorous fishes in more distant ocean basins. Our findings therefore suggest that the intestinal microbiome may be an important functional trait among these large-bodied consumers.

International audience; Fe-oxidizing bacteria of the family Gallionellaceae are major players in the Fe biogeochemical cycle in freshwater. These bacteria thrive in redox transition zones where they benefit from both high Fe concentrations and microaerobic conditions. We analysed the Gallionellaceae genomic diversity in an artesian hard-rock aquifer where redox transition zones develop (i) in the subsurface, where ancient, reduced groundwater mixes with recent oxygenated groundwater, and (ii) at the surface, where groundwater reaches the open air. Fifteen new draft genomes of Gallionellaceae representing to 11 candidate genera were recovered from the two redox transition zones. Sulfur oxidation genes were encoded in most genomes while denitrification genes were much less represented. One genus dominated microbial communities belowground and we propose to name it "Candidatus Houarnoksidobacter". The two transition zones were populated by completely different assemblages of Gallionellaceae despite the almost constant upward circulation of groundwater between the two zones. The processes leading to redox transition zones, oxygen diffusion at the surface or groundwater mixing in subsurface, appear to be a major driver of the Gallionellaceae diversity. Downloaded from https://academic.oup.com/femsec/advance-article-abstract/doi/10.1093/femsec/fiaa036/5800984 by CNRS user on 17 March 2020

Pistachio Bushy Top Syndrome (PBTS) is a recently emerged disease that has strongly impacted the pistachio industry in California, Arizona, and New Mexico. The disease is caused by two bacteria, designated PBTS1 that is related to Rhodococcus corynebacterioides and PBTS2 that belongs to the species R. fascians. Here, we assessed the pathogenic character of the causative agents and examined their chromosomal sequences to predict the presence of particular functions that might contribute to the observed co-occurrence and their effect on plant hosts. In diverse assays, we confirmed the pathogenicity of the strains on “UCB-1” pistachio rootstock and showed that they can also impact the development of tobacco species, but concurrently inconsistencies in the ability to induce symptoms were revealed. We additionally evidence that fas genes are present only in a subpopulation of pure PBTS1 and PBTS2 cultures after growth on synthetic media, that these genes are easily lost upon cultivation in rich media, and that they are enriched for in an in planta environment. Analysis of the chromosomal sequences indicated that PBTS1 and PBTS2 might have complementary activities that would support niche partitioning. Growth experiments showed that the nutrient utilization pattern of both PBTS bacteria was not identical, thus avoiding co-inhabitant competition. PBTS2 appeared to have the potential to positively affect the habitat fitness of PBTS1 by improving its resistance against increased concentrations of copper and penicillins. Finally, mining the chromosomes of PBTS1 and PBTS2 suggested that the bacteria could produce cytokinins, auxins, and plant growth-stimulating volatiles and that PBTS2 might interfere with ethylene levels, in support of their impact on plant development. Subsequent experimentation supported these in silico predictions. Altogether, our data provide an explanation for the observed pathogenic behavior and unveil part of the strategies used by PBTS1 and PBTS2 to interact with plants.

International audience; Trophic partitioning, defining how individuals or populations differ in their resource use, is expected to promote coexistence of sympatric species by reducing resource overlap. We used stable isotope measurements (delta C-13 and delta N-15) to address niche characteristics (delta C-13 and delta N-15 ranges, isotope convex hull and standard ellipse areas, mean nearest neighbour distances and trophic positions) and trophic partitioning of sympatric brown trout (Salmo trutta, n = 110) and European grayling (Thymallus thymallus, n = 63) in two sampling locations of a French river. Aquatic resources predominantly fuelled both species, yet both terrestrial resources (TER) and trophic positions (TP) were higher for trout (similar to 36 +/- 13% TER, 3.6 +/- 0.7 TP) than grayling (similar to 26 +/- 9% TER, 2.7 +/- 0.6 TP) supporting difference in their trophic niches. Isotope analyses showed that trout had a larger isotope niche than grayling suggesting more opportunistic trophic behaviour. Their isotopic overlapping was higher at the upstream site (isotopic nestedness = 0.8 +/- 0.1) than that at the downstream site (isotopic nestedness = 0.4 +/- 0.2). Euclidian distances of stable isotopes and TP for the two species increased with salmonid size, while aquatic resource use decreased with salmonid size. These results demonstrate an increase in isotopic niche partitioning and change in trophic attributes with ontogeny. Our study showed that despite relying on similar resources, these two sympatric salmonids exhibited clear trophic differences that were amplified with ontogeny. The consideration of fish ontogenetic dietary shift would hence be a determinant driver of the trophic niche partitioning for these sympatric salmonids.

Pollination is thought to be under positive density‐dependence, destabilising plant coexistence by conferring fitness disadvantages to rare species. Such disadvantage is exacerbated by interspecific competition but can be mitigated by facilitation and intraspecific competition. However, pollinator scarcity should enhance intraspecific plant competition and impose disadvantage on common over rare species (negative density‐dependence, NDD). We assessed pollination proxies (visitation rate, pollen receipt, pollen tubes) in a generalised plant community and related them to conspecific and heterospecific density, expecting NDD and interspecific facilitation due to the natural pollinator scarcity. Contrary to usual expectations, all proxies indicated strong intraspecific competition for common plants. Moreover interspecific facilitation prevailed and was stronger for rare than for common plants. Both NDD and interspecific facilitation were modulated by specialisation, floral display and pollinator group. The combination of intraspecific competition and interspecific facilitation fosters plant coexistence, suggesting that pollination can be a niche axis maintaining plant diversity., This work was supported by FAPESP (grants 2016/06434‐0 and 2018/02996‐0 to P.J.B.), CNPq (grants 436335/2018‐2 to M.W. and 302781/2016‐1 to M.S.) and CAPES (Ph.D. scholarship to N.S.S., Financial Code 001).

Simple Summary How congeneric species with similar realized niches manage to coexist is a central question in the study of biodiversity. Here, we examined the daily activity rhythm of two coexisting serow species in a mid-mountain humid evergreen broadleaf forest. We used camera traps in a five-year survey at Mt. Gaoligong, western Yunnan, China. We compared the daily activity rhythm of the rare red serow (Capricornis rubidus), a medium-sized solitary ungulate, with the coexisting Chinese serow (C. milneedwardsii milneedwardsii). Although their overall daily activity rhythms were similar, the rare red serow tended to range, feed, and stay vigilant from afternoon through midnight throughout the year. By contrast, Chinese serows preferred to be active from sunrise to noon in the wet season, but shifted their activities and behaviors to afternoon and midnight in the dry season. Interestingly, we found red serows sometimes ranging together with Chinese serows. When they encountered each other, red serows altered their activity patterns more notably, while Chinese serows significantly increased their activity level. These findings are understandable given their similar resource requirements. Although exploitative competitors, red and Chinese serow coexist by avoiding interference competition by altering their respective activity patterns in time. Abstract Surveying the activity rhythms of sympatric herbivorous mammals is essential for understanding their niche ecology, especially for how they partition resources and their mechanisms of coexistence. Over a five-year period, we conducted infrared camera-trapping to monitor the activity rhythms of coexisting red serow (Capricornis rubidus) and Chinese serow (C. milneedwardsii milneedwardsii) in the remote mountainous region of Pianma, Mt. Gaoligong, Yunnan, China. Cameras captured images of red serow and Chinese serow on 157 and 179 occasions, respectively. We used circular kernel density models to analyze daily activity rhythms and how temporal variations in activity ensure their co-existence. Although their overall activity levels and patterns were similar, temporal activity and behavior partitioning among the two species occurred during the wet season. Compared with Chinese serows, red serows exhibited less variable daily activity levels, patterns, as well as feeding and vigilance behaviors between seasons. When the two species occasionally ranged together, red serows tended to alter their activity pattern while Chinese serows significantly increased their activity level. Red serow and Chinese serow are exploitative competitors but coexist by altering their daily activity rhythms when in contact and changing activity patterns during the wet season, enabling their coexistence.

The subgenus Phyllodia (genus Pteronotus) comprises 9 species ranging from the western coast of Mexico to central Brazil, including Greater and Lesser Antilles. Two of them, Pteronotus rubiginosus and Pteronotus sp. 1, form an endemic South American clade within Phyllodia and are reported in sympatry for several localities in Guyana, Suriname, French Guiana, and northern Brazil. We herein performed a comprehensive investigation to fully characterize the cranial variation and genetic intraspecific structuring within this clade. We also integrated genetic, morphological, and acoustic evidence to formally describe the species previously reported as Pteronotus sp. 1. Specimens of P. rubiginosus occurring in sympatry with the new species have a more distinctive cranial phenotype than those from allopatric areas, suggesting character displacement as a potential force promoting divergence by decreasing resource competition or reproductive interactions between them. Although the 2 species are sympatric in several localities, the divergence in their echolocation calls also may be promoting resource partitioning at the microhabitat level, with P. rubiginosus foraging in less cluttered areas and the new species restricted to more cluttered areas. © 2018 American Society of Mammalogists, www.mammalogy.org.