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Leaf litter microbes collectively degrade plant polysaccharides, influencing land-atmosphere carbon exchange. An open question is how substrate complexity-defined as the structure of the saccharide and the amount of external processing by extracellular enzymes-influences species interactions. We tested the hypothesis that monosaccharides (i.e. xylose) promote negative interactions through resource competition, and polysaccharides (i.e. xylan) promote neutral or positive interactions through resource partitioning or synergism among extracellular enzymes. We assembled a three-species community of leaf litter-degrading bacteria isolated from a grassland site in Southern California. In the polysaccharide xylan, pairs of species stably coexisted and grew equally in coculture and in monoculture. Conversely, in the monosaccharide xylose, competitive exclusion and negative interactions prevailed. These pairwise dynamics remained consistent in a three-species community: all three species coexisted in xylan, while only two species coexisted in xylose, with one species capable of using peptone. A mathematical model showed that in xylose these dynamics could be explained by resource competition. Instead, the model could not predict the coexistence patterns in xylan, suggesting other interactions exist during biopolymer degradation. Overall, our study shows that substrate complexity influences species interactions and patterns of coexistence in a synthetic microbial community of leaf litter degraders.

Interspecific interactions are crucial in shaping ecosystem dynamics (Connell 1983, Tilman 1987, Barbosa and Castellanos 2005). Non-native ungulates have been introduced across the globe (Ferretti and Lovari 2014, Volery et al. 2021) and in environments where multiple invasives thrive, these co-occurring sympatric species may shift spatiotemporal patterns to minimize interspecific competition (Schoener 1974, Chesson 2000). Spatiotemporal shifts can lead to cascading effects to the native flora and fauna (Simberloff and Von Holle 1999). Given the potential negative impacts, understanding these interactions is vital for effective management of these ecosystems. Two invasive ungulates, the wild pig (Sus scrofa) and the Philippine deer (Rusa marianna), have inhabited much of Guam since their introduction in the 1600s and 1700s (Intoh 1986, Wiles et al. 1999) and both have been associated with significant ecological damage throughout the island (Conroy 1989). Despite sharing similar invasive roles, they seemingly coexist throughout areas of Guam. Subsequently, efforts are increasingly put forth to remove both species from partitioned areas at one time. To aid these efforts and understand invasive species interactions, we studied the seasonal spatiotemporal patterns of wild pigs and Philippine deer during February 2021-March 2022. Specifically, we used GPS collars from 39 wild pigs and 22 deer to examine spatial and temporal partitioning and assess dynamic spatiotemporal interactions between interspecific dyads at seasonal scales. We investigated spatial partitioning of wild pigs and deer by estimating the spatial overlap between home ranges and core areas of interspecific neighboring dyads. We estimated temporal overlap in diel activity to evaluate temporal partitioning between the species. Lastly, we examined dynamic spatiotemporal interactions, those that occur simultaneously in space and time, by estimating movement interactions between neighboring interspecific dyads to understand attraction and avoidance. We found spatial overlap between the species decreased significantly in core areas compared to home ranges in both seasons. Within home ranges, deer were approximately 3 times more likely to be within pig ranges than vice versa. This effect diminished at core areas such that deer were only 1.3× more likely to be within pig core ranges than vice versa. Temporal overlap of activity between wild pigs and deer was very high during dry and wet seasons, with overlapping activity peaks during crepuscular hours. At a critical distance threshold of 50m, we estimated 77 movement interactions from 58 dyad pairs over 3 seasons and found that only 2 (2.6%) and 4 (5.2%) movement interactions were considered avoidant and attractive, respectively, and the remaining 71 interactions (92.2%) were neutral.

Community dynamics within microbial mat assemblages are complex, likely involving intricate metabolic linkages. Interactions between microbes shape these communities, particularly in extreme habitats such as those found in the Middle Island Sinkhole (MIS), Lake Huron. Herein, euxinic waters resemble early-Earth ocean conditions, and diverse microbial groups form benthic mats. The goal of this study was to examine interspecific relationships among culturable cyanobacteria (two strains of Anagnostidinema) and diatoms (Craticula cuspidata and Nitzschia palea) isolated from MIS mats in a co-culture factorial experiment. Although most crosses showed limited interactions, a significant increase in abundance of one Anagnostidinema strain was found when grown with Craticula cuspidata compared to other taxa (P < 0.0001). Nitzschia palea growth was significantly reduced when grown with either strain of cyanobacteria (P = 0.0040). Addition of both cells and filtrates from C. cuspidata cultures caused increases in Anagnostidinema percent cover. Unique metabolic capabilities of C. cuspidata may benefit some cyanobacteria, and cyanobacteria may inhibit N. palea growth via interference competition. These interactions may be masked in the mat community in situ by environmental factors or other interspecific interactions, or allow species to survive in low abundance in an otherwise unfavorable habitat. [ABSTRACT FROM AUTHOR]

Niche partitioning according to time, space, or resources is the key to interspecific coexistence. Interactions among carnivore species are complex: interference is common, although positive relationships may develop through trophic facilitation. In turn, different behavioral responses to coexistence may be reported, ranging from avoidance to attraction, the outcome of which is highly dependent on the local environmental context. Here, we evaluated the temporal partitioning by analyzing spatiotemporal relationships between the red fox Vulpes vulpes and the European badger Meles meles in a Mediterranean?protected area for three full years, using intensive camera trapping. The two species showed similar temporal activity patterns, with a nocturnal activity and peaks at dawn and dusk. We found a substantial temporal overlap between red fox and badger (Δ > 0.78, on a 0‐1 scale). However, we detected some differences in temporal activity patterns across these species and no evidence of interspecific spatiotemporal avoidance. Previous work provided no evidence supporting spatial avoidance among the study species. Our results suggest a role of temporal partitioning at a finer scale during the night to facilitate interspecific coexistence. [ABSTRACT FROM AUTHOR]

Predator hunting strategies, such as stalking versus coursing behaviors, are hypothesized to influence antipredator behaviors of prey and can describe the movement behaviors of predators themselves. Predators and prey may alter their movement in relation to predator hunting modes, yet few studies have evaluated how these strategies influence movement behaviors of free‐ranging animals in a multiple‐predator, multiple‐prey system. We fit hidden Markov models (HMM) with movement data derived from >400 GPS‐collared ungulates and large predators in eastern Washington, USA. We used these models to test our hypotheses that stalking (cougars [Puma concolor]) and coursing (gray wolves [Canis lupus]) predators would exhibit different broad‐scale movement behaviors consistent with their respective hunting strategies in areas that increased the likelihood of encountering or capturing ungulate prey (e.g., habitats selected by deer [Odocoileus spp.]). Similarly, we expected that broadscale movement behaviors of prey would change in response to background levels of predation risk associated with each predator's hunting strategy. We found that predators and ungulate prey adjusted their broadscale movements in response to one another's long‐term patterns of habitat selection but not based on differences in predator‐hunting strategies. Predators changed their movement behaviors based on the type of prey, whereas ungulates generally reduced movement in areas associated with large predators, regardless of the predator's hunting strategy. Both predator and prey movements varied in response to landscape features but not necessarily based on habitat that would facilitate specific hunting behaviors. Our results suggest that predators and prey adjust their movements at broad temporal scales in relation to long‐term patterns of risk and resource distributions, potentially influencing their encounter rates with one another at finer spatiotemporal scales. Habitat features further influenced changes in movement, resulting in a complex combination of movement behaviors in multiple‐predator, multiple‐prey systems. [ABSTRACT FROM AUTHOR]

The article explores the role of ephemeral river islands in the Meta River in eastern Colombia as habitats for migratory songbirds from the northern and southern hemispheres during migration and the nonbreeding period. The islands emerge during the dry season, providing roosting and foraging sites for thousands of migratory birds. The study highlights the importance of understanding the habitat use and quality of nonbreeding areas for long-distance migrants and raises questions about the ecological associations, spatial-temporal dynamics, and conservation priorities of these ephemeral islands. [Extracted from the article]

The coevolutionary dynamic of host–parasite associations varies from strictly local adaptations to diffuse guild coevolution. How innate and acquired immune responses modulate host resistance to parasitism and how host specificity and geographic scaling affect the efficacy of host response have consequences for range dynamics and biological invasions.Using reciprocal transplant experiments, we tested whether local or diffuse coevolution shapes host response to parasitism in the host–parasite association between bitterling fishes and larval stages (glochidia) of freshwater mussels from Europe and East Asia.We found that glochidia initially indiscriminately attached to all study host species, but immune responses elicited significant differences in host responses within 24 h of infection, which intensified during glochidial development. European bitterlings were more resistant to European glochidia and Asian bitterlings to Asian glochidia, with the strongest geographic bias in resistance in the Asian bitterling hosts.This finding suggests a strong effect of local adaptation but also indicates the non‐negligible role of coevolutionary hotspots. Low natural glochidia load on bitterling species overall hence arise from competent immune response rather than glochidia avoidance behaviour. Bitterling immune response is primarily innate and not acquired.Overall, our data demonstrate the complex outcome of parasite pressure on the evolution of host resistance, and important role of geographically structured coevolution in shaping host response. [ABSTRACT FROM AUTHOR]

Summary Forest soils play a pivotal role as global carbon (C) sinks, where the dynamics of soil organic matter (SOM) are significantly influenced by ectomycorrhizal (ECM) fungi. While correlations between ECM fungal community composition and soil C storage have been documented, the underlying mechanisms behind this remain unclear. Here, we conducted controlled experiments using pure cultures growing on naturally complex SOM extracts to test how ECM fungi regulate soil C and nitrogen (N) dynamics in response to varying inorganic N availability, in both monoculture and mixed culture conditions. ECM species dominant in N‐poor soils exhibited superior SOM decay capabilities compared with those prevalent in N‐rich soils. Inorganic N addition alleviated N limitation for ECM species but exacerbated their C limitation, reflected by reduced N compound decomposition and increased C compound decomposition. In mixed cultures without inorganic N supplementation, ECM species with greater SOM decomposition potential facilitated the persistence of less proficient SOM decomposers. Regardless of inorganic N availability, ECM species in mixed cultures demonstrated a preference for C over N, intensifying relatively labile C compound decomposition. This study highlights the complex interactions between ECM species, their nutritional requirements, the nutritional environment of their habitat, and their role in modifying SOM. [ABSTRACT FROM AUTHOR]

This study investigates the diversity and ecological dynamics of macroalgae in Maxwell Bay, King George Island, Antarctica, focusing on species distribution, substrate composition, and interspecific interactions. Across nine survey sites, 31 macroalgal species were recorded, with 12 species identified as significant due to their considerable relative frequency, coverage, and biomass. Palmaria decipiens was the most dominant species in terms of frequency and coverage, while Desmarestia anceps had the highest biomass. The study revealed distinct substrate preferences, with P. decipiens favoring cobble and mud substrates, and Himantothallus grandifolius associating predominantly with pebble substrates. A core group of species, including Plocamium sp., H. grandifolius, Picconiella plumosa, Iridaea sp., and Trematocarpus antarcticus, exhibited strong ecological interactions characterized by high substrate similarity and mutual affinity. In contrast, pioneer species like P. decipiens and Monostroma hariotii showed lower affinity with other species, reflecting their early successional roles. These findings enhance our understanding of the complex interspecific relationships within Antarctic macroalgal assemblage and provide valuable baseline data for future ecological studies in the region. [ABSTRACT FROM AUTHOR]

What do seabirds perceive about the world? How do they do so? And how do they use the information available to them to make foraging decisions? Social cues provide seabirds with information about the location of prey. This can, of course, be passive and not involve higher‐order cognitive processes (e.g. simple conspecific or heterospecific attraction). However, seabirds display many behaviours that promote learning and the transmission of information between individuals: the vast majority of seabirds are colonial living, have an extended juvenile phase that affords them time to learn, routinely form intra‐ and interspecific associations, and can flexibly deploy a combination of foraging tactics. It is worth evaluating their foraging interactions in light of this. This review describes how seabirds use social information both at the colony and at sea to forage, and discusses the variation that exists both across species and amongst individuals. It is clear that social interactions are a critical and beneficial component of seabird foraging, with most of the variation concerning the way and extent to which social information is used, rather than whether it is used. While it may seem counterintuitive that large groups of potential competitors congregating at a patch can result in foraging gains, such aggregations can alter species dynamics in ways that promote coexistence. This review explores how competitive interference at a patch can be mitigated by behavioural modifications and niche segregation. Utilising others for foraging success (e.g. via social cues and facilitation at a patch) is likely to make population declines particularly damaging to seabirds if the quantity or quality of their social foraging interactions is reduced. Environmental changes have the potential to disrupt their social networks and thus, how these species obtain food and transfer information. [ABSTRACT FROM AUTHOR]

Freshwater macroinvertebrates can connect tropical forests and stream food webs by consuming both terrestrially and aquatically produced foods, but direct observations of nocturnal feeding behavior in these natural ecosystems are rare. Observational data on decapods feeding behavior are limited partly because they are cryptic and often forage at night to avoid predators and competitors. We hypothesized that freshwater decapods forage on riparian fruit fall based on its relatively high energy and nutrient content. We used underwater cameras to video record night-time foraging under dim red light. Palm fruits (Acrocomia aculeata (Jacq.) Lodd. ex Mart.) were added to determine rates of feeding responses among crabs (Silviocarcinus australis Magalhães and Turkay, 1996) and shrimp (Macrobrachium amazonicum Heller, 1862) in a spring-fed, clear-water stream in the state of Mato Grosso do Sul, Brazil. Within 30 min, shrimp located the fruit, and within 60 min, crabs began shredding the pulp of the palm fruit. Crabs fed on the palm fruits, on average five times longer than shrimp and produced pieces of palm fruit pulp that some shrimp consumed without aggressively interacting with the crab. Small fish also consumed some palm pulp particles. This interaction network is an example of fruit-fall processing based on indirect facilitation among different types of consumers. [ABSTRACT FROM AUTHOR]

Horizon scans have emerged as a valuable tool to anticipate the incoming invasive alien species (IAS) by judging species on their potential impacts. However, little research has been conducted on quantifying actual impacts and assessing causes of species‐specific vulnerabilities to particular IAS due to persistent methodological challenges. The underlying interspecific mechanisms driving species‐specific vulnerabilities therefore remain poorly understood, even though they can substantially improve the accuracy of risk assessments. Given that interspecific interactions underlying ecological impacts of IAS are often shaped by phenological synchrony, we tested the hypothesis that temporal mismatches in breeding phenology between native species and IAS can mitigate their ecological impacts. Focusing on the invasive American bullfrog (Lithobates catesbeianus), we combined an environmental DNA (eDNA) quantitative barcoding and metabarcoding survey in Belgium with a global meta‐analysis, and integrated citizen‐science data on breeding phenology. We examined whether the presence of native amphibian species was negatively related to the presence or abundance of invasive bullfrogs and whether this relationship was affected by their phenological mismatches. The field study revealed a significant negative effect of increasing bullfrog eDNA concentrations on native amphibian species richness and community structure. These observations were shaped by species‐specific vulnerabilities to invasive bullfrogs, with late spring‐ and summer‐breeding species being strongly affected, while winter‐breeding species remained unaffected. This trend was confirmed by the global meta‐analysis. A significant negative relationship was observed between phenological mismatch and the impact of bullfrogs. Specifically, native amphibian species with breeding phenology differing by 6 weeks or less from invasive bullfrogs were more likely to be absent in the presence of bullfrogs than species whose phenology differed by more than 6 weeks with that of bullfrogs. Taken together, we present a novel method based on the combination of aqueous eDNA quantitative barcoding and metabarcoding to quantify the ecological impacts of biological invaders at the community level. We show that phenological mismatches between native and invasive species can be a strong predictor of invasion impact regardless of ecological or methodological context. Therefore, we advocate for the integration of temporal alignment between native and IAS's phenologies into invasion impact frameworks. [ABSTRACT FROM AUTHOR]

Globalisation, climate change and international trade are the factors contributing to the spread of Aedes albopictus (Diptera: Culicidae) and Ae. aegypti into new areas. In newly invaded habitats, these non‐native species can serve as arbovirus disease vectors or increase the risk of disease spill over. These mosquitoes continue to emerge in new areas where they have or will have overlapping ranges with other resident mosquito species. The study investigates how invasive Aedes mosquitoes compete with the native Culex pipiens in Türkiye, which might affect the overall mosquito population dynamics and disease transmission risks. Both Aedes species exhibited contrasting responses to interspecific competition with Cx. pipiens. While Ae. albopictus suffers reduced emergence primarily in larger containers with abundant food, Ae. aegypti surprisingly thrives in mixed cultures under all food conditions. Adult Cx. pipiens emergence drops by half against Ae. albopictus and under specific conditions with Ae. aegypti. Competition influences mosquito size differently across species and life stages. Culex pipiens females grow larger when competing with Ae. aegypti, potentially indicating resource advantage or compensatory strategies. However, Ae. albopictus size shows more nuanced responses, suggesting complex interactions at play. Understanding how invasive and native mosquitoes interact with each other can provide insights into how they adapt and coexist in shared habitats. This knowledge can inform effective control strategies. The study highlights the differential responses of invasive Aedes species and the potential for managing populations based on their competitive interactions with the native Cx. pipiens. It can contribute to improved monitoring and prediction systems for the spread of invasive mosquitoes and the associated disease risks. [ABSTRACT FROM AUTHOR]

Microbes are key drivers of global biogeochemical cycles, and their functional roles arey dependent on temperature. Large population sizes and rapid turnover rates mean that the predominant response of microbes to environmental warming is likely to be evolutionary, yet our understanding of evolutionary responses to temperature change in microbial systems is rudimentary. Natural microbial communities are diverse assemblages of interacting taxa. However, most studies investigating the evolutionary response of bacteria to temperature change are focused on monocultures. Here, we utilize high-throughput experimental evolution of bacteria in both monoculture and community contexts along a thermal gradient to determine how interspecific interactions influence the thermal adaptation of community members. We found that community-evolved isolates tended toward higher maximum growth rates across the temperature gradient compared to their monoculture-evolved counterparts. We also saw little evidence of systematic evolutionary change in the shapes of bacterial thermal tolerance curves along the thermal gradient. However, the effect of community background and selection temperature on the evolution of thermal tolerance curves was variable and highly taxon-specific,with some taxa exhibiting pronounced changes in thermal tolerance while others were less impacted. We also found that temperature acted as a strong environmental filter, resulting in the local extinction of taxa along the thermal gradient, implying that temperature-driven ecological change was a key factor shaping the community background upon which evolutionary selection can operate. These findings offer novel insight into how community background impacts thermal adaptation. [ABSTRACT FROM AUTHOR]

Social interactions with heterospecifics can yield important insights into the flexibility of behaviour and the role of learning in communication. Recently, the honeybee dance, a unique symbolic communication system to communicate positions in space, has been shown to involve learning. We asked if this communication system could potentially be learned by members of a species not normally using this communication system, the bumblebee(Bombus terrestris)—indicating that learning might have been at the origins of dance communication. We used mixed-species colonies of bumblebees and honeybees (Apis millefera) to investigate how the readiness to first establish contact with dancers might develop in uninformed bumblebee foragers. Over a month of observations, we recorded and classified a series of behavioural patterns in newly emerged honeybees introduced into queenright bumblebee colonies. A small subset of the introduced honeybees was able to establish in the nests and displayed their typical behavioural patterns, including homing, dance communication, trophallaxis, and social grooming. Remarkably, grooming and trophallaxis were also displayed to heterospecifics, and bumblebees accepted both, including food offered through trophallaxis, even though this behaviour is not normally used by bumblebees. However, bumblebees never attended honeybees’ waggle dances. Our results contribute to insights about bee social behaviour and cognition by providing a fascinating example of the adaptive use and modification of innate behaviour. [ABSTRACT FROM AUTHOR]

Symbiotic relationships shape ecological communities and often involve more than two species. Yet few experimental studies examine the impact of symbioses involving three species, particularly any mediating role of third parties, and none involving symbioses of predators.We investigated experimentally the synergistic and antagonistic fitness effects of three symbiotic spider predators across a broad latitudinal range and involving different species combinations.The three‐dimensional web complex of Cyrtophora spiders is a habitat patch to different associates—species of Argyrodes and web‐building Leucauge spider guests. Our field experiments, which manipulated the presence of each guest species and determined the subsequent host weight change, revealed a remarkable consistency in fitness outcomes across the three populations, with the consequences of the interactions between two species depending upon the services provided by a third.Cyrtophora hosts intercepted more prey when web‐building Leucauge guests were present and thus gained more weight. In contrast, Argyrodes guests exerted a fitness cost on their Cyrtophora host, but only when Leucauge guests were absent. A comparison of the prey consumed by Cyrtophora hosts and Argyrodes guests revealed that their diets (reflected in the size of prey) overlapped less in the presence of Leucauge web‐building guests.Our novel experimental study highlights the importance of exploring synergistic effects in multi‐species symbioses. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Introduction: Maize/soybean intercropping is a common cropping practice in Chinese agriculture, known to boost crop yield and enhance soil fertility. However, the role of below-ground interactions, particularly root exudates, in maintaining intercropping advantages in soybean/maize intercropping systems remains unclear. Methods: This study aimed to investigate the differences in root exudates between intercropping and monocropping systems through two pot experiments using metabolomics methods. Multiple omics analyses were conducted to explore correlations between differential metabolites and the community of Arbuscular Mycorrhizal Fungi (AMF), shedding light on the mechanisms underlying the dominance of intercropping from the perspective of root exudates-soil microorganism interactions. Results and discussion: The study revealed that intercropping significantly increased the types and contents of root exudates, lowered soil pH, increased the availability of nutrients like available nitrogen (AN) and available phosphorus (AP), and enhanced AMF colonization, resulting in improving the community composition of AMF. Besides, root exudates in intercropping systems differed significantly from those in monocropping, with 41 and 39 differential metabolites identified in the root exudates of soybean/maize, predominantly amino acids and organic acids. The total amount of amino acids in the root exudates of soybean intercropping was 3.61 times higher than in monocropping. Additionally, the addition of root exudates significantly improved the growth of soybean/maize and AMF colonization, with the mycorrhizal colonization rate in intercropping increased by 105.99% and 111.18% compared to monocropping, respectively. The identified metabolic pathways associated with root exudates were closely linked to plant growth, soil fertility improvement, and the formation of AMF. Correlation analysis revealed a significant relationship (P < 0.05) between certain metabolites such as tartaric acid, oxalic acid, malic acid, aspartic acid, alanine, and the AMF community. Notably, the photosynthetic carbon fixation pathway involving aspartic acid showed a strong association with the function of Glomus_f_Glomerace, the dominant genus of AMF. A combined analysis of metabolomics and high throughput sequencing revealed that the root exudates of soybean/maize intercropping have direct or indirect connections with AMF and soil nutrients. Conclusion: This suggests that the increased root exudates of the soybean/maize intercropping system mediate an improvement in AMF community composition, thereby influencing soil fertility and maintaining the advantage of intercropping. [ABSTRACT FROM AUTHOR]

The analysis of mechanisms underlying prey use and selection is crucial for understanding the potential for apex predators to shape ecological processes across trophic levels. Significant implications for the conservation and management of ecosystems can ensue, especially in human-modified landscapes characterised by the recent recovery of apex predators, such as those of Europe. Generalist predators may show frequency-dependent prey selection, leading to prey switching; however, there is no ubiquitous support for positive relationships between prey abundance and prey selection. In a protected area recently recolonised by the wolf Canis lupus and hosting abundant wild prey (>20 individuals/km2), we assessed prey use and selection (>3000 wolf scats analysed) throughout 7 years since wolf settlement (April 2016-to-March 2023), during which prey density was relatively stable. Wolf diet was dominated by wild boar Sus scrofa and fallow deer Dama dama (>70 % of occurrences and volume); the roe deer Capreolus capreolus and coypu Myocastor coypus represented main secondary prey. The wolf showed a clear prey switching throughout the study. In the first two years, the fallow deer was the main prey and was positively selected. Then, wild boar replaced fallow deer as main prey, and was positively selected, with a progressive decrease in the use of fallow deer throughout the years. Selection indices of wild boar were negatively associated with those of fallow deer. The relationship between selection indices and population density was inconsistent across species, being negative for the wild boar and weakly positive for the fallow deer, although the latter showed no sharp decline in the area. Concurrent studies showed increased diurnal activity of fallow deer and a consequent reduced temporal overlap with the wolf throughout years since the settlement of this predator, suggesting temporal avoidance. By supporting a minor role of prey density in mediating prey switching, our results suggest a major role of other factors (e.g., antipredator behavioural responses). Alternative substantial prey are important to buffer apex predators not only towards changes in the abundance of main prey, but also towards the effects of other factors potentially reducing prey detectability, e.g., antipredator behaviour.

Understanding how non-trophic social systems respond to environmental gradients is still a challenge in animal ecology, particularly in comparing changes in species composition to changes in interspecific interactions. Here, we combined long-term monitoring of mixed-species bird flocks, data on participating species evolutionary history and traits, to test how elevation affected community assemblages and interspecific interactions in flock social networks. Elevation primarily affected flocks through reassembling interspecific associations rather than modifying community assemblages. Specifically, flock networks at higher elevations (compared to low elevations) had stronger interspecific associations (larger average weighted degree), network connectivity (enhanced network density) and fewer subnetworks. A phylogenetic and functional perspective revealed that associations between similar species weakened, whereas connections between dissimilar and/or random species were unchanged or strengthened with elevation. Likewise, network assortativity for the traits of vertical stratum and breeding period declined with elevation. The overall pattern is a change from modular networks in the lowlands, where species join flocks with other species that have matching traits, to a more open, random system at high elevations. Collectively, this rewiring of interspecific networks across elevational gradients imparts network stability and resiliency and makes mixed-species flocks less sensitive to local extinctions caused by harsh environments.

Conservation successes in Europe have sparked the recovery of apex predators, which may affect the populations of mesopredators. The mesopredator release hypothesis (MRH) predicts that a decline in apex predators triggers a ‘release’ of mesopredators from suppression. We expanded the MRH to include predictions of inverse responses following increases in apex predator abundance or distribution. We examined European mesopredator responses to changes in apex predator populations and evaluated the extended MRH's explanatory power. We examined the results of 47 studies on European predators for supporting evidence, mixed evidence, no evidence, or contrasting evidence for the extended MRH. Out of 38 apex predator – mesopredator pairings, 10 predominantly supported the extended MRH, while others provided limited or no support. In 23 instances across 17 pairings, mesopredator responses contradicted predictions. Initial findings suggest the extended MRH better predicts mesopredator responses in pairings with intermediate to large body size differences and in pairings where mesopredators primarily hunt. Our results reveal non‐uniform mesopredator responses to changing apex predator populations. This emphasises the complexity of predator interactions, which extends beyond suppression. We suggest the MRH's scope is more restricted than previously thought, cautioning against overreliance on the MRH as a default expectation for European mesopredator responses to apex predator population changes. [ABSTRACT FROM AUTHOR]

1. Ecosystem engineering freshwater bivalves, burrowing in the substratum and accumulating shell deposits, transform bottom habitats. Especially the invasive Asian bivalve Sinanodonta woodiana (SW), due to its rapid growth, large size, and high fecundity, can affect benthic communities. Here, we determined its effect on habitat selection and behaviour of endangered native bivalves, Anodonta cygnea and Unio tumidus. 2. We conducted laboratory preference assays (Experiment 1: choice between two substrata) exposing the native bivalves to pure sand (control), shells (several densities on the sand surface or burrowed), or living SW. Then, we tested their locomotion and burrowing (Experiment 2) on pure sand and substrata contaminated with shells or living SW. 3. In Experiment 1, native bivalves avoided shells, but not living SW. Burrowed and larger shells were avoided compared with those on the surface and smaller ones, respectively. 4. In Experiment 2, U. tumidus exposed to SW delayed activity initiation (in response to living bivalves), increased locomotion (living bivalves, surface shells), and reduced burrowing depth (living bivalves, all shells). Anodonta cygnea exposed to SW reduced locomotion speed (living bivalves, shells), and reduced burrowing duration (burrowed shells) and depth (living bivalves, burrowed shells). 5. SW (especially shell beds) constitutes another emerging threat to native bivalves, impairing their burrowing and inducting active avoidance. As SW expands its distribution with climate warming, the range and strength of its impact is likely to increase, reducing the area available to native bivalves, exposing them to environmental dangers (due to burrowing limitation) and deteriorating physical condition (energetic resources used for excessive locomotion). [ABSTRACT FROM AUTHOR]

Birds and ants co‐occur in most terrestrial ecosystems and engage in a range of interactions. Competition, mutualism and predation are prominent examples of these interactions, but there are possibly many others that remain to be identified and characterized. This study provides quantitative estimates of the frequency of toe amputations resulting from ant bites in a population of migratory red‐necked nightjars (Caprimulgus ruficollis) monitored for 15 years (2009–2023) in S Spain, and identifies the attacker(s) based on taxonomic analyses of ant‐mandible remains found on injured toes. Less than 1% of examined adults (N = 369) missed one or more toes. The analysis of ant remains identified African army ants (Dorylus sp.) as the primary cause of toe amputations in nightjars and revealed that body parts of the attacker may remain attached to the birds even after intercontinental migration. No cases of severe damage were observed in juveniles (N = 269), apart from the mandible of a Messor barbarus – a local ant species – attached to one of the teeth of the characteristic comb of the medial toe of nightjars. The incidence of ant‐bite damage may appear unimportant for nightjar populations, but this might not be true if only birds that manage to survive their injuries and potential complications (e.g. severe bleeding and sepsis from opportunistic infections) return from the tropics. More field studies, ideally in tropical areas, that incorporate routine examination of ant‐induced injuries into their protocols are needed to understand the true incidence and eco‐evolutionary implications of antagonistic ant‐bird interactions. [ABSTRACT FROM AUTHOR]

Behavioural interactions between alien invasive fishes and native fishes is considered one of the drivers of native fish decline. However, there are few experimental studies on their behavioural interactions at the individual level. In this study, we investigated the behavioural interactions between the threatened native killifish Valencia letourneuxi, and the alien invasive Eastern mosquitofish Gambusia holbrooki, thought to induce the killifish's rapid population decline. The aim was to assess aggressive behaviours, disruption in activity, stress levels, boldness, forging efficiency and shelter use by the native fish in the presence of the mosquitofish. Interspecies interactions were assessed in a three-tiered experimental setup, i.e. in an empty arena, in the presence of an artificial cover, and during feeding, using two opponents at each trial. The behaviours recorded and assessed were nips, following, approach, moving/immobile, top/bottom, erratic movement, cover use, feeding and latency to exit. The results showed that the mosquitofish was bolder, followed the native species, spent significantly less time under the cover and consumed food, as opposed to no following by the native species, significantly higher cover use and time immobile, as avoidance behaviours, and zero feeding in the presence of the mosquitofish. More significantly, the native species received direct aggression by the mosquitofish, as opposed to no aggression at all exhibited by it. Future research needs, as well as the conservation implications of our findings are briefly discussed. [ABSTRACT FROM AUTHOR]

Secondary forests are increasingly important for biodiversity conservation and ecosystem functioning. Yet, we know little on how species interactions shift across the wide range of life history strategies in the context of forest succession, especially for non‐trophic animal social systems.Using data from mixed‐species flocks (hereafter MSFs) and life history and morphological traits from the 'fast‐slow' continuum, we utilized a novel combination of network theory and trait‐based ecology to examine the assembly of associations of MSFs among species with different fast‐slow strategies across stages of forest succession that exhibit different degrees of forest complexity.MSFs formed the most connected and cohesive network in the intermediate successional stage. In contrast, we observed the least connected and cohesive network in the early stage, and a strongly connected but intermediately cohesive network in the late stage. Fast species with smaller body size and mass, and larger clutch size, were gradually replaced by slow species during succession. Interspecific associations generally shifted from those among similarly fast species (early stage) to associations between fast and slow species (intermediate stage), and finally to those among similarly slow species (late stage).We suggest that vegetation complexity (e.g. tree size, height, diversity and canopy cover), related to the availability of resources and number of niches, shaped the network structure and functional composition of MSFs. Although the late successional forests play an irreplaceable role in protecting forest specialists (i.e. slow species), intermediate stage forests should be also protected, because the large‐sized networks formed by MSFs at intermediate stages can simultaneously conserve more species with varying ecological strategies. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Limiting resources are often unevenly distributed among competing consumers, as larger, more aggressive, fast growing, early emerging, or rapidly reproducing species disproportionately exploit food or habitat. In such cases, asymmetric competition can occur (i.e., when limited resources are divided up unequally among individuals or species), resulting in stronger negative effects for some species and comparatively weaker effects for others. We hypothesize that the accessibility of food web pathways influences asymmetric competition among stream fishes. To test this hypothesis, we studied the interactions of invasive brown trout (Salmo trutta) with native Rio Grande sucker (Catostomus plebeius or Pantosteus plebeius) and Rio Grande chub (Gila pandora) in mountain streams of New Mexico, USA, from 2020 to 2021. Our study found support for the hypothesis that the accessibility of food web pathways drives asymmetric competition in mountain stream fishes, as native chub and sucker grew at slower rates than invasive brown trout across all observed body sizes. Our conclusion is evidenced by (1) strong diet overlap driven by benthic macroinvertebrates that (2) were important in fueling the growth of native fishes but were also (3) disproportionately exploited by trout. Because trout fed on small aquatic invertebrates, large crayfish, other fish, and inputs of terrestrial prey, they could incorporate energy from differing food web pathways, whereas native fishes were mostly limited to small benthic prey (and chubs fed on terrestrial arthropods). As trout, chub, and sucker competed for small benthic prey, trout could also incorporate other sources of food, whereas chub and sucker had fewer options. Although two or more species may compete for one resource, their rates of growth and production are also dependent on, and fueled by, other food web pathways. Our work demonstrates that such food web pathways help explain differences in growth and production between invasive and native fishes. Our findings show that tracking energy flows through the different food web pathways provides a useful and intuitive means of describing the important sources of food (i.e., the trophic basis of production) that fuel growth and production and sheds light on the processes that drive asymmetric competition. [ABSTRACT FROM AUTHOR]

BACKGROUND: Phoma stem canker is an economically important disease of oilseed rape, caused by two co‐existing fungal pathogen species, Leptosphaeria maculans (Plenodomus lingam) and Leptosphaeria biglobosa (Plenodomus biglobosus). Leptosphaeria maculans produces a phytotoxin called sirodesmin PL. Our previous work showed that L. biglobosa has an antagonistic effect on the production of sirodesmin PL if it is simultaneously co‐inoculated with L. maculans. However, the effects of sequential co‐inoculation on interspecific interactions between the two pathogens are not understood. RESULTS: The interactions between L. maculans and L. biglobosa were investigated in liquid culture by inoculation with L. maculans first, followed by L. biglobosa sequentially at 1, 3, 5 or 7 days later and vice versa; the controls were inoculated with L. maculans only, L. biglobosa only, or L. maculans and L. biglobosa simultaneously. The results showed that L. biglobosa inhibited the growth of L. maculans, the production of both sirodesmin PL and its precursors if L. biglobosa was inoculated before, or simultaneously with, L. maculans. However, the antagonistic effects of L. biglobosa were lost if it was co‐inoculated 5 or 7 days after L. maculans. CONCLUSION: For the first time, the results of this study provided evidence that the timing when L. maculans and L. biglobosa meet significantly influences the outcome of the interspecific competition between them. Leptosphaeria biglobosa can inhibit the production of sirodesmin PL and the growth of L. maculans if it is inoculated before L. maculans or less than 3 days after L. maculans in liquid culture. There is a need to further investigate the timing of co‐inoculation on interactions between L. maculans and L. biglobosa in their host plants for improving the control of phoma stem canker. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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Species interactions such as facilitation and competition play a crucial role in driving species range shifts. However, density dependence as a key feature of these processes has received little attention in both empirical and modelling studies. Herein, we used a novel, individual‐based treeline model informed by rich in situ observations to quantify the contribution of density‐dependent species interactions to alpine treeline dynamics, an iconic biome boundary recognized as an indicator of global warming. We found that competition and facilitation dominate in dense versus sparse vegetation scenarios respectively. The optimal balance between these two effects was identified at an intermediate vegetation thickness where the treeline elevation was the highest. Furthermore, treeline shift rates decreased sharply with vegetation thickness and the associated transition from positive to negative species interactions. We thus postulate that vegetation density must be considered when modelling species range dynamics to avoid inadequate predictions of its responses to climate warming. [ABSTRACT FROM AUTHOR]

Interspecific interactions can influence species' activity and movement patterns. In particular, species may avoid or attract each other through reactive responses in space and/or time. However, data and methods to study such reactive interactions have remained scarce and were generally limited to two interacting species. At this time, the deployment of camera traps opens new opportunities but adapted statistical techniques are still required to analyze interaction patterns with such data. We present the multivariate Hawkes process (MHP) and show how it can be used to analyze interactions between several species using camera trap data. Hawkes processes use flexible pairwise interaction functions, allowing us to consider asymmetries and variations over time when depicting reactive temporal interactions. After describing the theoretical foundations of the MHP, we outline how its framework can be used to study interspecific interactions with camera trap data. We design a simulation study to evaluate the performance of the MHP and of another existing method to infer interactions from camera trap‐like data. We also use the MHP to infer reactive interactions from real camera trap data for five species from South African savannas (impala Aepyceros melampus, greater kudu Tragelaphus strepsiceros, lion Panthera leo, blue wildebeest Connochaetes taurinus and Burchell's zebra Equus quagga burchelli). The simulation study shows that the MHP can be used as a tool to benchmark other methods of interspecific interaction inference and that this model can reliably infer interactions when enough data are considered. The analysis of real data highlights evidence of predator avoidance by prey and herbivore–herbivore attraction. Lastly, we present the advantages and limits of the MHP and discuss how it can be improved to infer attraction/avoidance patterns more reliably. As camera traps are increasingly used, the multivariate Hawkes process provides a promising framework to decipher the complexity of interactions structuring ecological communities. [ABSTRACT FROM AUTHOR]

Metacommunity theory seeks to explain how local and regional processes contribute to the organisation of biological communities. Recent conceptual frameworks of this theory indicate that the dynamics of populations and communities are jointly established by dispersal, species responses to environmental conditions and biotic interactions dependent on species density. Here, we use hierarchical joint species distribution modelling to verify the effects of environmental factors (at multiple spatial scales), drainage network configuration, spatial autocorrelation and interspecific interactions on the structure of fish assemblages in terra‐firme streams in the Eastern Brazilian Amazon. Thirty streams were sampled in two field surveys, and 89 species were collected in total. Our results confirm the effects of limited dispersal, environmental conditions (at multiple scales) and the configuration of the drainage network on the dynamics of these assemblages. Furthermore, our results suggest that interspecific interactions are less relevant for the structuring of fish metacommunities in small Amazonian headwater streams. Abiotic factors like drainage networks and environmental heterogeneity were better predictors of species distributions than co‐occurrence patterns with potential competitors or predators. [ABSTRACT FROM AUTHOR]

This study investigates the diversity and ecological dynamics of macroalgae in Maxwell Bay, King George Island, Antarctica, focusing on species distribution, substrate composition, and interspecific interactions. Across nine survey sites, 31 macroalgal species were recorded, with 12 species identified as significant due to their considerable relative frequency, coverage, and biomass. Palmaria decipiens was the most dominant species in terms of frequency and coverage, while Desmarestia anceps had the highest biomass. The study revealed distinct substrate preferences, with P. decipiens favoring cobble and mud substrates, and Himantothallus grandifolius associating predominantly with pebble substrates. A core group of species, including Plocamium sp., H. grandifolius, Picconiella plumosa, Iridaea sp., and Trematocarpus antarcticus, exhibited strong ecological interactions characterized by high substrate similarity and mutual affinity. In contrast, pioneer species like P. decipiens and Monostroma hariotii showed lower affinity with other species, reflecting their early successional roles. These findings enhance our understanding of the complex interspecific relationships within Antarctic macroalgal assemblage and provide valuable baseline data for future ecological studies in the region.

We observed this behaviour, previously studied only in North America and as a rare occurrence, on each of the three visits, one per year, we made to the same site, in Italy. Honey bees Apis mellifera L. preferred collecting pollen from red-tailed bumble bees Bombus lapidarius L. than directly from flowers of the woolly thistle Cirsium eriophorum (L.). In another site, which equally had this thistle species as the only plant in bloom, but fewer bumble bees, honey and bumble bees foraged concomitantly on the same flowers avoiding interspecific contacts. In both sites, the honey bees showed easier foraging in the presence of male, than of less tolerant worker, bumble bees. In a third site, the honey bees preferred foraging independently on the smaller flowers of the Tyrol thistle Centaurea nigrescens Willd., while the bumble bees preferred the woolly thistle. Therefore, when plants offer few foraging choices, honey bees may visit less preferred large composite flowers where a crowd of bumble bees hampers their usual foraging mode, but little-reactive males offer pollen collection from their furry bodies, to which honey bees specialize. [ABSTRACT FROM AUTHOR]

Research Highlight: Jachowski, D. S., Marneweck, C. J., Olfenbuttel, C., & Harris, S. N. (2024). Support for the size‐mediated sensitivity hypothesis within a diverse carnivore community. Journal of Animal Ecology, https://doi.org/10.1111/1365‐2656.13916. A current paradigm in ecological research suggests that top predators are suitable sentinel species to identify ecosystem dysfunctions and monitor the effects of climate change. However, the adequacy of top predators to systematically take this function may be mistakenly inferred or unintentionally conflated from the fact that these species are regarded as biodiversity indicators or keystone, umbrella and flagship species in most ecosystems. Regarding terrestrial mammalian carnivores (order Carnivora), some researchers recently suggested that the smaller species likely possess a higher sensitivity to environmental changes than large carnivores because of their biological attributes and their intermediate position in food webs. To test this hypothesis, Jachowski et al. (2024) used camera trapping followed by occupancy and structural equation modelling to explore the dynamics of a diverse carnivore community and the factors that influence them. Their results confirmed that small carnivores are more sensitive to habitat changes and are interconnected by a greater number of significant pathways compared with larger carnivores. This support for the size‐mediated sensitivity hypothesis strengthens the proposition that small carnivores (and other mid‐rank predators) are ideal sentinel species for monitoring the effects of the wide range of contemporary and future environmental changes. Time will tell whether this new 'middle‐out ecology' paradigm will be considered in future global change studies. [ABSTRACT FROM AUTHOR]

Competition over resources often leads to intra‐ and interspecific interactions, which can be detrimental to the individuals involved. Thus, natural selection should favor communication systems that reliably convey information regarding the relative competitive abilities of an individual, reducing the need for physically damaging confrontation. Body size, sex, age, relatedness, and ornamentation are important factors determining dominance across diverse taxa in intraspecific interactions. These traits, when perceptible, may serve as signals across species in guilds that have frequent interspecific interactions. Hummingbirds provide a tractable system to study such community dynamics due to their high frequency of interactions, variable ornamentation, diverse body sizes, fast metabolism, and large overlap in resource utilization. Even in this system, potential interactions between morphology and coloration are rarely accounted for together when analyzing dominance between species. We take a novel approach to understanding interspecific dominance by assessing behavior, morphology, and coloration across different types of behavioral interactions. Across 11 tropical montane hummingbird species, we find that dominance is predicted by wing size and some metrics of plumage coloration. However, the biological significance of these factors varies between the different dominance behaviors performed. These results inform our understanding of interspecific signaling and its role in the evolution of intraguild communication and resource competition. [ABSTRACT FROM AUTHOR]

The main function of birdsong is to attract mates and defend territories among conspecifics, but little is known about the potential of this behavior in generating interactions among co-existing bird species that signal at the same time. Different hypotheses have been put forward to explain the mechanisms that govern signaling in crowded acoustic spaces, including competition for acoustic space, interspecific territoriality, environmental filters, and acoustic social facilitation. We tested these hypotheses in a forest bird community by studying the behavioral, acoustic, and ecological characteristics of 13 co-occurring species. We used passive recordings to assess the magnitude and the determinants of heterospecific song co-occurrence (i.e., when different species sing at the same time and place), and playback experiments to quantify the propensity of birds to sing if stimulated by heterospecific songs. Birds more frequently sang with species with dissimilar songs. In the breeding season, they also actively sang after the playback of other species, especially if these had dissimilar songs, and occasionally after non-avian unfamiliar playbacks. Heterospecific songs may trigger song utterance because they indicate a predator-free environment, or reduce predation risk through dilution effects, and these benefits may be maximized if there is little acoustic similarity. In line with ecological theory on community assembly mechanisms, these results are compatible with limiting similarity (species with similar songs sing at different times) and suggests social facilitation between phenotypically dissimilar species. These potential biotic interactions through songs may represent a mechanism that leads to bird species coexistence and are worth exploring at the community level. Significance statement: It is generally assumed that bird species avoid acoustic overlap with birds singing similar songs, but there is also evidence of active interspecific territoriality through song displays between pairs of species. Community-wide responses through songs have never been investigated in birds, and to fill this knowledge gap we performed both observations and experiments on multiple coexisting species. Birds tended to sing with species with more dissimilar songs and they were also actively stimulated to sing when the songs of species with dissimilar songs were played back. An interaction between species with dissimilar songs therefore emerged, potentially yielding anti-predatory benefits. Such active behavior, which would have gone unnoticed if observations only were performed, involves multiple species, and therefore may represent a community-wide mechanism of species coexistence. [ABSTRACT FROM AUTHOR]

Palaeomycological material has rarely been reported in Mexican localities, especially parasitic fungi. In this paper, we present the first formal report of an interaction between an entomopathogenic fungus and an insect trapped in the Miocene amber from Chiapas, Mexico. The described syninclusion corresponds to two well-developed fungal fruiting bodies and a third one in development, assigned to the order Hypocreales (Ascomycota: Sordariomycetes), emerging from the thorax and abdomen of a termite (Blattodea: Mastotermitidae). This syninclusion represents a remarkable example of biological interactions in ancient tropical environments reflected in the fossil record. [ABSTRACT FROM AUTHOR]

Although the advent of high‐resolution GPS tracking technology has helped increase our understanding of individual and multispecies behavior in wildlife systems, detecting and recording direct interactions between free‐ranging animals remains difficult. In 2023, we deployed GPS collars equipped with proximity sensors (GPS proximity collars) on brown bears (Ursus arctos) and moose (Alces alces) as part of a multispecies interaction study in central Sweden. On 6 June, 2023, a collar on an adult female moose and a collar on an adult male bear triggered each other's UHF signal and started collecting fine‐scale GPS positioning data. The moose collar collected positions every 2 min for 89 min, and the bear collar collected positions every 1 min for 41 min. On 8 June, field personnel visited the site and found a female neonate moose carcass with clear indications of bear bite marks on the head and neck. During the predation event, the bear remained at the carcass while the moose moved back and forth, moving toward the carcass site about five times. The moose was observed via drone with two calves on 24 May and with only one remaining calf on 9 June. This case study describes, to the best of our knowledge, the first instance of a predation event between two free ranging, wild species recorded by GPS proximity collars. Both collars successfully triggered and switched to finer‐scaled GPS fix rates when the individuals were in close proximity, producing detailed movement data for both predator and prey during and after a predation event. We suggest that, combined with standard field methodology, GPS proximity collars placed on free‐ranging animals offer the ability for researchers to observe direct interactions between multiple individuals and species in the wild without the need for direct visual observation. [ABSTRACT FROM AUTHOR]

Prey adjust their antipredator behavioral tactics to minimize the risk of an encounter with predators. Spatiotemporal responses of prey to predators have been reported, but the nature of antipredator response is not ubiquitous and it is the object of increasing interest, especially considering the recent recovery of large carnivores in Europe, and the potential for behavioral antipredator responses to elicit consequences at the ecosystem level. We have tested multiple antipredator responses by fallow deer Dama dama to wolf Canis lupus in a Mediterranean protected area recently recolonized by this apex predator. Through intensive camera trapping, we tested for temporal and spatial association between predator and prey, and we have also studied deer vigilance in forest habitats where focal observations are usually impossible. Wolf detection rates were spatially associated with those of fallow deer. Accordingly, no evidence was found for fallow deer avoiding sites with higher predator detection rates. Temporal activity patterns were significantly different between the 2 species, with the wolf being mainly nocturnal whereas fallow deer was active especially during daylight. A comparison with a preliminary study strongly suggests an increase in the diurnal activity of fallow deer along with the stabilization of wolf presence in the area. Both the rate and the duration of vigilance of female fallow deer increased with the local frequency of wolf activity. We suggest an antipredator response based on temporal—rather than spatial—avoidance, as well as increased vigilance. [ABSTRACT FROM AUTHOR]

Abstract Birds and ants co‐occur in most terrestrial ecosystems and engage in a range of interactions. Competition, mutualism and predation are prominent examples of these interactions, but there are possibly many others that remain to be identified and characterized. This study provides quantitative estimates of the frequency of toe amputations resulting from ant bites in a population of migratory red‐necked nightjars (Caprimulgus ruficollis) monitored for 15 years (2009–2023) in S Spain, and identifies the attacker(s) based on taxonomic analyses of ant‐mandible remains found on injured toes. Less than 1% of examined adults (N = 369) missed one or more toes. The analysis of ant remains identified African army ants (Dorylus sp.) as the primary cause of toe amputations in nightjars and revealed that body parts of the attacker may remain attached to the birds even after intercontinental migration. No cases of severe damage were observed in juveniles (N = 269), apart from the mandible of a Messor barbarus – a local ant species – attached to one of the teeth of the characteristic comb of the medial toe of nightjars. The incidence of ant‐bite damage may appear unimportant for nightjar populations, but this might not be true if only birds that manage to survive their injuries and potential complications (e.g. severe bleeding and sepsis from opportunistic infections) return from the tropics. More field studies, ideally in tropical areas, that incorporate routine examination of ant‐induced injuries into their protocols are needed to understand the true incidence and eco‐evolutionary implications of antagonistic ant‐bird interactions.

Abstract Limiting resources are often unevenly distributed among competing consumers, as larger, more aggressive, fast growing, early emerging, or rapidly reproducing species disproportionately exploit food or habitat. In such cases, asymmetric competition can occur (i.e., when limited resources are divided up unequally among individuals or species), resulting in stronger negative effects for some species and comparatively weaker effects for others. We hypothesize that the accessibility of food web pathways influences asymmetric competition among stream fishes. To test this hypothesis, we studied the interactions of invasive brown trout (Salmo trutta) with native Rio Grande sucker (Catostomus plebeius or Pantosteus plebeius) and Rio Grande chub (Gila pandora) in mountain streams of New Mexico, USA, from 2020 to 2021. Our study found support for the hypothesis that the accessibility of food web pathways drives asymmetric competition in mountain stream fishes, as native chub and sucker grew at slower rates than invasive brown trout across all observed body sizes. Our conclusion is evidenced by (1) strong diet overlap driven by benthic macroinvertebrates that (2) were important in fueling the growth of native fishes but were also (3) disproportionately exploited by trout. Because trout fed on small aquatic invertebrates, large crayfish, other fish, and inputs of terrestrial prey, they could incorporate energy from differing food web pathways, whereas native fishes were mostly limited to small benthic prey (and chubs fed on terrestrial arthropods). As trout, chub, and sucker competed for small benthic prey, trout could also incorporate other sources of food, whereas chub and sucker had fewer options. Although two or more species may compete for one resource, their rates of growth and production are also dependent on, and fueled by, other food web pathways. Our work demonstrates that such food web pathways help explain differences in growth and production between invasive and native fishes. Our findings show that tracking energy flows through the different food web pathways provides a useful and intuitive means of describing the important sources of food (i.e., the trophic basis of production) that fuel growth and production and sheds light on the processes that drive asymmetric competition.

Controversy exists around owned dogs’ impacts in public open spaces, with concerns about dogs’ impact on wildlife, including birds. Leashing dogs in public open spaces offers a tractable way of reducing dogs’ deleterious impacts on birds. Although dogs in public spaces are often unleashed, some dogs roam freely, whilst other unleashed dogs remain close to their owners. It is currently unknown whether birds can perceive and incorporate subtle differences in the leash status of approaching, but non-roaming, dogs into their escape decisions. We compare escape responses of a common urban bird, the magpie-lark Grallina cyanoleuca, in parks in Melbourne, Australia, to standardized approaches by a walker and a dog, which was either leashed or not leashed (but with the dog at the same distance from the walker). Flight-initiation distances, the distance between the lark and dog when escape commenced, did not vary between treatments. However, the unleashed dog evoked more intense responses (mostly flying away) than the leashed dog (mostly walking away). Thus, this species appears to perceive unleashed dogs as especially threatening, independent of their roaming behavior. Our findings suggest that leashing may be an effective way to reduce dog disturbance to wildlife, even for non-roaming dogs.

Abstract Although the advent of high‐resolution GPS tracking technology has helped increase our understanding of individual and multispecies behavior in wildlife systems, detecting and recording direct interactions between free‐ranging animals remains difficult. In 2023, we deployed GPS collars equipped with proximity sensors (GPS proximity collars) on brown bears (Ursus arctos) and moose (Alces alces) as part of a multispecies interaction study in central Sweden. On 6 June, 2023, a collar on an adult female moose and a collar on an adult male bear triggered each other's UHF signal and started collecting fine‐scale GPS positioning data. The moose collar collected positions every 2 min for 89 min, and the bear collar collected positions every 1 min for 41 min. On 8 June, field personnel visited the site and found a female neonate moose carcass with clear indications of bear bite marks on the head and neck. During the predation event, the bear remained at the carcass while the moose moved back and forth, moving toward the carcass site about five times. The moose was observed via drone with two calves on 24 May and with only one remaining calf on 9 June. This case study describes, to the best of our knowledge, the first instance of a predation event between two free ranging, wild species recorded by GPS proximity collars. Both collars successfully triggered and switched to finer‐scaled GPS fix rates when the individuals were in close proximity, producing detailed movement data for both predator and prey during and after a predation event. We suggest that, combined with standard field methodology, GPS proximity collars placed on free‐ranging animals offer the ability for researchers to observe direct interactions between multiple individuals and species in the wild without the need for direct visual observation.

Host–parasite dynamics involve coevolutionary arms races, which may lead to host specialization and ensuing diversification. Our general understanding of the evolution of host specialization in brood parasites is compromised by a restricted focus on bird and insect lineages. The cuckoo catfish (Synodontis multipunctatus) is an obligate parasite of parental care of mouthbrooding cichlids in Lake Tanganyika. Given the ecological and taxonomic diversity of mouthbrooding cichlids in the lake, we hypothesized the existence of sympatric host‐specific lineages in the cuckoo catfish. In a sample of 779 broods from 20 cichlid species, we found four species parasitized by cuckoo catfish (with prevalence of parasitism of 2%–18%). All parasitized cichlids were from the tribe Tropheini, maternal mouthbrooders that spawn over a substrate (rather than in open water). Phylogenetic analysis based on genomic (ddRAD sequencing) and mitochondrial (Dloop) data from cuckoo catfish embryos showed an absence of host‐specific lineages. This was corroborated by analyses of genetic structure and co‐ancestry matrix. Within host species, parasitism was not associated with any individual characteristic we recorded (parent size, water depth), but was costly as parasitized parents carried smaller clutches of their own offspring. We conclude that the cuckoo catfish is an intermediate generalist and discuss costs, benefits and constraints of host specialization in this species and brood parasites in general. [ABSTRACT FROM AUTHOR]

Invasive species and chemical pollution both threaten biodiversity. Here, we discuss how pollution, through its impacts on wildlife behaviour, shapes invasion dynamics by altering species interactions. Addressing knowledge gaps will have implications for the management of invasive species and conservation of native ecosystems in an increasingly toxic world. [ABSTRACT FROM AUTHOR]

Aim: Occurring in five distinct global regions, Mediterranean‐type ecosystems (MTEs) include both centres of agricultural production and hotspots of extratropical biodiversity – particularly for plants and bees. Considerable research has addressed the persistence of highly diverse biological communities within MTEs, despite their typically long histories of anthropogenic and natural disturbance. However, important questions remain, especially regarding the limits of ecological resilience in the face of accelerating environmental change. Here, we explore current knowledge regarding the effects of disturbance on MTE plant–pollinator communities. Location: Mediterranean Basin, California, Cape Province in South Africa, Central Chile and Southern South‐Western Australia. Taxa Studied: Flowering plants and pollinators (insects, birds and mammals). Methods: We reviewed the available literature about MTE plant–pollinator communities via a systematic search that yielded 234 case studies. We analysed this dataset to quantify research efforts across regions and taxonomic groups, the proportion of surveys addressing ecological interactions (i.e. rather than only taxonomic diversity) and the availability of work addressing community responses to specific stressors (viz. climate change, landscape alteration, fire, farming, grazing, urbanization and species introductions). Results: Current knowledge on MTE plant–pollinator communities is dominated by work from the northern Mediterranean Basin, while the Southern Hemisphere and California are markedly understudied by comparison. Taxonomic coverage is similarly uneven, with 58% of studies focusing only on a single pollinator group. Furthermore, less than half of the surveys address ecological networks. Finally, despite some pioneering work addressing fire, climate and species introductions, only 13% focus on the impact of stressors on interaction networks. Outlook: Based on our findings, we identify a need for coordinated international research efforts focusing on (i) community‐level studies, observational and experimental, (ii) ecological networks, (iii) functional traits mediating post‐disturbance recovery and (iv) impacts of combined/synergistic stressors. Progress in these areas will facilitate predictions about the long‐term impacts of global change on MTE plant–pollinator communities. [ABSTRACT FROM AUTHOR]