Search

Abstract Seed dispersal and predation play important roles in plant life history by contributing to recruitment patterns in the landscape. Mast-seeding – extensive synchronized inter-annual variability in seed production – is known to influence the activity of acorn consumers at source trees, but little is known about its effect on post-dispersal predation. We conducted a planting experiment over three years to investigate the relationship between habitat-level post-dispersal predation and landscape-wide acorn production of three sympatric oak species (Quercus spp.). We measured post-dispersal predation in three oak-dominated habitats – savanna (under Q. lobata), forest edge (under Q. agrifolia), and woodland (under Q. douglasii) – as well as in chaparral and open fields. Overall, landscape-level predation was similarly high among study years, averaging 61.4%. Neither species nor mass of planted acorns affected predation. Habitat had a significant effect on post-dispersal predation risk with acorns disappearing most rapidly in chaparral and least rapidly in woodlands. However, a significant interaction between year and habitat (Z = −4.5, P < 0.001) showed that the hierarchy of predation risk among habitats was inconsistent among years. Using annual acorn census data from local populations of each oak species, we found that predation risk in oak-dominated habitats was significantly and positively related to acorn production of the overstory species (Z = −9.53, P = 0.009). Our findings add to growing evidence that seed dispersal, predation, and regeneration are context-dependent on annual variation in community-level seed production, and we discuss the potential consequences of these dynamics on oak recruitment and animal behavior. Highlights • Post-dispersal acorn predation [PDP] in mimicked bird caches averaged 61.4% across three study years. • PDP risk was not affected by acorn species or mass. • PDP varied significantly among habitat types: acorns disappeared most rapidly in chaparral and least rapidly in woodlands. • A significant interaction effect showed that the hierarchy of PDP risk among habitats was inconsistent among years. • PDP in oak-dominated habitats was context-dependent and positively related to acorn production of the canopy species. [ABSTRACT FROM AUTHOR]

Abstract: Our understanding of the niche concept will remain limited while the quantity and range of different food types eaten remain a dominant proxy for niche breadth, as this does not account for the broad ecological context that governs diet. Linking nutrition, physiology and behaviour is critical to predict the extent to which a species adjusts its nutritional niche breadth at the levels of prey (“prey composition niche,” defined as the range of prey compositions eaten) and diet (“realized nutritional niche” is the range of diets composed through feeding on the prey). Here, we studied adult chick‐rearing Australasian gannets Morus serrator to propose an integrative approach using sea surface temperature anomalies (SSTa), geographic location and bathymetry over different years, to explore their relationship with the nutritional composition of prey and diets (i.e. prey composition and nutritional niche breadth), habitat use and foraging behaviour. We found that gannets feed on prey that varied widely in their nutritional composition (have a broad prey composition niche), and composed diets from these prey that likewise varied in composition (have a broad realized nutritional niche), suggesting generalism at two levels of macronutrient selection. Across seasons, we established “nutritional landscapes” (hereafter nutriscapes), linking the nutritional content of prey (wet mass protein‐to‐lipid ratio—P:L) to the most likely geographic area of capture and bathymetry. Nutriscapes varied in their P:L from 6.06 to 15.28, over time, space and bathymetry (0–150 m). During warm water events (strong positive SSTa), gannets expanded their foraging habitat, increased their foraging trip duration and consumed prey and diets with low macronutrient content (wet mass proportions of P and L). They were also constrained to the smallest prey composition and realized nutritional niche breadths. Our findings are consistent with previous suggestions that dietary generalism evolves in heterogeneous environments, and provide a framework for understanding the nutritional goals in wild marine predators and how these goals drive ecological interactions and are, in turn, ultimately shaped by environmental fluctuations. [ABSTRACT FROM AUTHOR]

ABSTRACT: The breeding and non‐breeding ‘castes’ of eusocial insects provide a striking example of role‐specific selection, where each caste maximises fitness through different morphological, behavioural and physiological trait values. Typically, queens are long‐lived egg‐layers, while workers are short‐lived, largely sterile foragers. Remarkably, the two castes are nevertheless produced by the same genome. The existence of inter‐caste genetic correlations is a neglected consequence of this shared genome, potentially hindering the evolution of caste dimorphism: alleles that increase the productivity of queens may decrease the productivity of workers and vice versa, such that each caste is prevented from reaching optimal trait values. A likely consequence of this ‘intralocus caste antagonism’ should be the maintenance of genetic variation for fitness and maladaptation within castes (termed ‘caste load’), analogous to the result of intralocus sexual antagonism. The aim of this review is to create a research framework for understanding caste antagonism, drawing in part upon conceptual similarities with sexual antagonism. By reviewing both the social insect and sexual antagonism literature, we highlight the current empirical evidence for caste antagonism, discuss social systems of interest, how antagonism might be resolved, and challenges for future research. We also introduce the idea that sexual and caste antagonism could interact, creating a three‐way antagonism over gene expression. This includes unpacking the implications of haplodiploidy for the outcome of this complex interaction. [ABSTRACT FROM AUTHOR]

Predator-prey theory predicts that in the presence of multiple types of predators using a common prey, predator facilitation may result as a consequence of contrasting prey defense mechanisms, where reducing the risk from one predator increases the risk from the other. While predator facilitation is well established in natural predator-prey systems, little attention has been paid to situations where human hunters compete with natural predators for the same prey. Here, we investigate hunting-mediated predator facilitation in a hunter-predator-prey system. We found that hunter avoidance by roe deer ( Capreolus capreolus) exposed them to increase predation risk by Eurasian lynx ( Lynx lynx). Lynx responded by increasing their activity and predation on deer, providing evidence that superadditive hunting mortality may be occurring through predator facilitation. Our results reveal a new pathway through which human hunters, in their role as top predators, may affect species interactions at lower trophic levels and thus drive ecosystem processes. [ABSTRACT FROM AUTHOR]

Vireo atricapilla (Black-capped Vireo) is an endangered songbird whose habitat use has been well studied in central portions of its breeding range, which is characterized by successional vegetation communities. To expand our understanding of habitat use as it relates to reproductive success, we studied Black-capped Vireo habitat use at the territory and nest-site scales in southwest Texas in 2009 and 2010, an area characterized by xeric and stable vegetation communities. We measured vegetation in territories and at nests to evaluate the influence of habitat variables on nest parasitism and nest survival. Our results showed that Black-capped Vireo nest-site use in southwest Texas differed from that in breeding areas of central Texas and Oklahoma. Black-capped Vireos in southwest Texas used nest sites with a wide range of woody cover (70 ±13%) and used Juniperus spp. (junipers) as a nest substrate proportionately more than its availability in territories, which is contradictory to previously published literature. Nest parasitism increased significantly with greater nest height, likely due to increased visibility to Molothrus ater (Brown-headed Cowbird). Increasing height of vertical cover above the nest was associated with decreased overall nest survival, likely because nests placed in habitat with taller vegetation are more susceptible to avian predators and Brown-headed Cowbird parasitism. Unlike the findings of studies conducted in the northern part of the species'breeding range, we found that parasitism did not increase the likelihood of depredation or abandonment. Our results indicate that Black-capped Vireo habitat structure and composition, as well as factors influencing nest success in Southwest Texas, differ from their breeding habitat in central Texas and Oklahoma, indicating that management guidelines need to be regi on-specific. [ABSTRACT FROM AUTHOR]

Some parasites move from one host to another via trophic transmission, the consumption of the parasite (inside its current host) by its future host. Feeding links among free-living species can thus be understood as potential transmission routes for parasites. As these links have different dynamic and structural properties, they may also vary in their effectiveness as trophic transmission routes. That is, some links may be better than others in allowing parasites to complete their complex life cycles. However, not all links are accessible to parasites as most are restricted to a small number of host taxa. This restriction means that differences between links involving host and non-host taxa must be considered when assessing whether transmission routes for parasites have different food web properties than other links. Here we use four New Zealand lake food webs to test whether link properties (contribution of a link to the predator's diet, prey abundance, prey biomass, amount of biomass transferred, centrality, and asymmetry) affect trophic transmission of parasites. Critically, we do this using both models that neglect the taxonomy of free-living species and models that explicitly include information about which free-living species are members of suitable host taxa. Although the best-fit model excluding taxonomic information suggested that transmission routes have different properties than other feeding links, when including taxonomy, the best-fit model included only an intercept. This means that the taxonomy of free-living species is a key determinant of parasite transmission routes and that food-web properties of transmission routes are constrained by the properties of host taxa. In particular, many intermediate hosts (prey) attain high biomasses and are involved in highly central links while links connecting intermediate to definitive (predator) hosts tend to be dynamically weak. [ABSTRACT FROM AUTHOR]

Ocean acidification and warming, driven by anthropogenic CO2 emissions, are considered to be among the greatest threats facing marine organisms. While each stressor in isolation has been studied extensively, there has been less focus on their combined effects, which could impact key ecological processes. We tested the independent and combined effects of short-term exposure to elevated CO2 and temperature on the predator--prey interactions of a common pair of coral reef fishes (Pomacentrus wardi and its predator, Pseudochromis fuscus). We found that predator success increased following independent exposure to high temperature and elevated CO2. Overall, high temperature had an overwhelming effect on the escape behaviour of the prey compared with the combined exposure to elevated CO2 and high temperature or the independent effect of elevated CO2. Exposure to high temperatures led to an increase in attack and predation rates. By contrast, we observed little influence of elevated CO2 on the behaviour of the predator, suggesting that the attack behaviour of P. fuscus was robust to this environmental change. This is the first study to address how the kinematics and swimming performance at the basis of predator--prey interactions may change in response to concurrent exposure to elevated CO2 and high temperatures and represents an important step to forecasting the responses of interacting species to climate change. [ABSTRACT FROM AUTHOR]

Increased predation risk is considered a cost of having conspicuous colours, affecting the anti-predator behaviour of colourful animals. However, this is difficult to test, as individual factors often covary with colour and behaviour. We used alarm call playback and behavioural observations to assess whether individual birds adjust their response to risk according to their plumage colour. Male superb fairy-wrens (Malurus cyaneus) change from a dull brown to conspicuous blue plumage each year, allowing the behaviour of different coloured birds to be compared while controlling for within-individual effects. Because the timing of colour change varies among males, blue and brown birds can also be compared at the same time of year, controlling for seasonal effects on behaviour. While blue, fairy-wrens fled more often in response to alarm calls, and took longer to emerge from cover. Blue fairywrens also spent more time foraging in cover and being vigilant. Group members appeared to benefit from the presence of blue males, as they reduced their response to alarms, and allocated less time to sentinel behaviour when a blue male was close by. We suggest that fairy-wrens perceive themselves to be at a higher risk of predation while in conspicuous plumage and adjust their behaviour accordingly. [ABSTRACT FROM AUTHOR]

Large carnivores' fear of the human 'super predator' has the potential to alter their feeding behaviour and result in human-induced trophic cascades. However, it has yet to be experimentally tested if large carnivores perceive humans as predators and react strongly enough to have cascading effects on their prey. We conducted a predator playback experiment exposing pumas to predator (human) and non-predator control (frog) sounds at puma feeding sites to measure immediate fear responses to humans and the subsequent impacts on feeding. We found that pumas fled more frequently, took longer to return, and reduced their overall feeding time by more than half in response to hearing the human 'super predator'. Combined with our previous work showing higher kill rates of deer in more urbanized landscapes, this study reveals that fear is the mechanism driving an ecological cascade from humans to increased puma predation on deer. By demonstrating that the fear of humans can cause a strong reduction in feeding by pumas, our results support that non-consumptive forms of human disturbance may alter the ecological role of large carnivores. [ABSTRACT FROM AUTHOR]

Predation is a fundamental interaction between species, yet it is unclear what escape strategies are effective for prey survival. Classical theory proposes that prey should either escape in a direction that conforms to a performance optimum or that is random and therefore unpredictable. Here, we show that larval zebrafish (Danio rerio) instead use a mixed strategy that may be either random or directed. This was determined by testing classic theory with measurements of the escape direction in response to a predator robot. We found that prey consistently escaped in a direction contralateral to the robot when approached from the side of the prey's body. At such an orientation, the predator appeared in the prey's central visual field and the contralateral response was consistent with a model of strategy that maximizes the distance from the predator. By contrast, when the robot approached the rostral or caudal ends of the body, and appeared in the prey's peripheral vision, the escape showed an equal probability of a contralateral or ipsilateral direction. At this orientation, a contralateral response offered little strategic advantage. Therefore, zebrafish larvae adopt an escape strategy that maximizes distance from the threat when strategically beneficial and that is otherwise random. This sensory-mediated mixed strategy may be employed by a diversity of animals and offers a new paradigm for understanding the factors that govern prey survival. [ABSTRACT FROM AUTHOR]

Constriction is an evolutionarily and functionally important behavior that many snakes use to subdue a variety of prey. However, little work has examined the effects of prey size on constriction performance. Furthermore, many snakes are known to feed even while previously consumed prey remain in the stomach. This temporary increase in mass may place constraints on subsequent performance. To test these effects, I investigated constriction performance in eastern kingsnakes Lampropeltis getula handling different sizes and quantities of rodent prey in two experiments by measuring coil length and peak constriction pressure. In the first experiment, constriction coil length and peak constriction pressure did not differ significantly between snakes feeding on either 'small' (5% relative prey mass, RPM) or 'large' (15% RPM) rodent prey. However, there was a significant interaction between prey size and repeated feeding. Snakes that had previously consumed large meals had significantly shorter coil lengths and lower peak constriction pressures when fed for a second time (reductions of 60 and 51%, respectively). In Experiment 2, snakes offered five sequential, similarly sized prey (@ 7% RPM), showed a regular decrease in coil length and peak constriction pressure across sequential feeding trials. During the final (fifth) trials, snakes used 45.7% shorter coils and exerted 50.1% lower peak constriction pressures. Thus, prey size alone did not affect constriction performance, but predation performance was significantly affected by the prior consumption of prey ≥7% RPM, and performance was further reduced during additional feeding trials. [ABSTRACT FROM AUTHOR]

Animals can adapt their activity patterns throughout the circadian cycle. Prey may use moonlight as a predation risk cue and allocate their activity to lower risk periods. Here, we assessed moon transit influence on the activity allocation of nocturnal mammalian prey, in the presence of a predator (pumas, Puma concolor), during different moon phases, through camera trapping in Central Amazon. Thirty camera traps were installed 2 km apart from each other in each of our three study sites. Prey record distributions were assessed across the moon cycle, and their daily activity patterns were described in each moon phase. The record distributions of pacas ( Cuniculus paca) ( N = 262) and armadillos ( Dasypus sp.) ( N = 244) were concentrated in darker nights, contrasting with red brocket deer ( Mazama americana) ( N = 123) and pumas ( N = 31), whose records were evenly distributed through the moon cycle. Yet, every prey was found to avoid the brighter times of the night regardless of the moon phase. These findings suggest prey can shift the temporal distribution of their activities under different moon phases when predators are present, perhaps in response to predation risk variations. [ABSTRACT FROM AUTHOR]

Prey individuals are often distributed heterogeneously in the environment, and their abundances and relative availabilities vary among patches. A foraging predator should maximize energetic gains by selectively choosing patches with higher prey density. However, catching behaviorally responsive and group-forming prey in patchy environments can be a challenge for predators. First, they have to identify the profitable patches, and second, they must manage the prey's sophisticated anti-predator behavior. Thus, the forager and its prey have to continuously adjust their behavior to that of their opponent. Given these conditions, the foraging predator's behavior should be dynamic with time in terms of foraging effort and prey capture rates across different patches. Theoretically, the allocation of its time among patches of behaviorally responsive prey should be such that it equalizes its prey capture rates across patches through time. We tested this prediction in a model system containing a predator (little egret) and group-forming prey (common gold fish) in two sets of experiments in which (1) patches (pools) contained equal numbers of prey, or in which (2) patches contained unequal densities of prey. The egret equalized the prey capture rate through time in both equal and different density experiments. [ABSTRACT FROM AUTHOR]

Predation can strongly influence the evolution of prey species by selecting for defensive phenotypes that reduce the risk of predation. Although cannibalism is frequent in predators and is known to strongly influence predator- prey dynamics, it is largely neglected when studying the evolution of phenotypic defences in prey. Changes in cannibalism can alter the abundance, size-structure, and even phenotypes within predator populations, and thereby change the numerical and per-capita effects driving the selection pressure on defensive phenotypes in prey. In the present study, we experimentally manipulated the presence and absence of cannibalism in predatory salamander larvae Hynobius retardatus (Dunn) and examined how this affects the expression of and selection pressure on inducible defensive phenotype (bulgy phenotype) in its prey, Rana pirica (Matsui) tadpoles. In the absence of cannibalism, salamanders were generally not sufficiently large to consume tadpoles, tadpoles did not express the defensive phenotype, and all phenotypes had equally high survival. By contrast, cannibalism of salamanders accelerated growth rates, leading to the development of 'giant' cannibalistic morphs that were able to consume tadpoles. Importantly, only in the presence of these giant cannibals did tadpoles express a defensive 'bulgy' phenotype that had significantly higher survival rates than phenotypes without this defence, indicating that cannibalism altered the selective regime for defensive traits in prey. The results of the present study demonstrate that cannibalism can drive trait evolution in predator-prey systems and suggest that we cannot predict how changes in numerical effects in predator populations affect selection regimes on prey traits without accounting for concurrent changes in predator per-capita effects. [ABSTRACT FROM AUTHOR]

The “Lévy Foraging Hypothesis” promotes Lévy walk (LW) as the best strategy to forage for patchily but unpredictably located prey. This strategy mixes extensive and intensive searching phases in a mostly cue-free way through strange, scale-free kinetics. It is however less efficient than a cue-driven two-scale Composite Brownian walk (CBW) when the resources encountered are systematically detected. Nevertheless, it could be assumed that the intrinsic capacity of LW to trigger cue-free intensive searching at random locations might be advantageous when resources are not only scarcely encountered but also so cryptic that the probability to detect those encountered during movement is low. Surprisingly, this situation, which should be quite common in natural environments, has almost never been studied. Only a few studies have considered “saltatory” foragers, which are fully “blind” while moving and thus detect prey only during scanning pauses, but none of them compared the efficiency of LW vs. CBW in this context or in less extreme contexts where the detection probability during movement is not null but very low. In a study based on computer simulations, we filled the bridge between the concepts of “pure continuous” and “pure saltatory” foraging by considering that the probability to detect resources encountered while moving may range from 0 to 1. We showed that regularly stopping to scan the environment can indeed improve efficiency, but only at very low detection probabilities. Furthermore, the LW is then systematically outperformed by a mixed cue-driven/internally-driven CBW. It is thus more likely that evolution tends to favour strategies that rely on environmental feedbacks rather than on strange kinetics. [ABSTRACT FROM AUTHOR]

Predation and competition are highly influential factors determining space use in foraging animals, and ultimately contribute to the spatial heterogeneity observed within habitats. Here we investigated the influence of competition and predation on space and resource use via continuous video transect observations - a tool that has not previously been employed for this purpose. This study therefore also evaluates video data as a pragmatic tool to study community interactions in the deep sea. Observations were compiled from 15 video transects spanning five submarine canyons in the Bay of Biscay, France. Substrate choice, positioning on the coral, echinoid aggregate size, and the presence/ absence of predators (e.g. fish and decapods) as well as competitors (both interand intra-specific) were recorded. Two dominant co-existing echinoid taxa, echinothurids and Cidaris cidaris (3188 total observations), were observed in the study. For the echinothurids, no significant trends were detected in the interand intra-specific competition data. For Cidaris cidaris, significant shifts in substrate use were correlated to the presence of inter-specific competitors (echinothurids), whereby an increase in dead coral substrate usage was observed. Highly significant patterns were detected amongst echinoids near fish and decapod predators. A shift to the base of the coral infra-structure was correlated to the presence of fish, and fewer individuals were observed in the open areas of the reef and a greater number were found in the mid and top sections of the coral when in the presence of decapods. Aggregates formed irrespective of the presence of predators. Aggregations are likely to form for feeding and reproduction rather than for defensive purposes; and migration along the coral infra-structure may be a predator-driven behaviour as echinoids seek refuge from predators. Predation risk might play a stronger - or more detectable - role in structuring echinoid space and resource use in deep-sea coral habitats. In addition, the study successfully detected patterns in the video data thereby demonstrating its potential usefulness for similar ecological studies on other deep-dwelling megabenthos. [ABSTRACT FROM AUTHOR]

The transition from a planktonic larval stage to a benthic or demersal juvenile stage is a crucial event in the life history of coral reef fishes, and recruitment success has a strong influence on reef-fish population size. Post-settlement predation is thought to limit recruitment success. Most studies on post-settlement predation have focused on piscivorous reef fishes. However, recent studies in the tropical Pacific Ocean suggest that blood-feeding ectoparasites may also be an important source of predation. Here we provide further evidence that a gnathiid ectoparasite is capable of such "micropredation" on settlement-stage fish in the eastern Caribbean Sea. On 12 occasions in May–August, 2014 and 2015, during plankton light-trap recovery, we observed postsettlement fishes from the families Apogonidae, Bothidae, Gobiidae, Labrisomidae, and Tripterygiidae with attached ectoparasitic juvenile gnathiid isopods. In one laboratory experiment in which 10 settlement-stage French grunt, Haemulon flavolineatum (Desmarest, 1823), were fed upon by an average of one gnathiid per fish, all fish died compared to none in the control group. In a subsequent experiment in which individual settlement-stage French grunt were exposed to 0–3 gnathiids each, all 50 fish that were fed upon by at least one gnathiid died, compared with only one of 78 that were not fed on by any gnathiids. Combined with observations on damselfishes from the Pacific Ocean, these findings suggest that gnathiids are capable of micropredation on larval fish at time of reef settlement and that micropredation should be further evaluated as a factor affecting success of settlement and thus recruitment success of coral reef fishes. [ABSTRACT FROM AUTHOR]

Theory predicts that ecological communities of many interacting species are unstable, despite the fact that complex ecosystems persist in nature. A recent theoretical study hypothesised that coexistence of antagonism and mutualism can stabilise a community and even give rise to a positive complexity–stability relationship. Here, using a theoretical model, we extended the earlier hypothesis to include competition as a third major interaction type, and showed that interaction-type diversity generally enhances stability of complex communities. Furthermore, we report a new finding that the hierarchically structured antagonistic interaction network is important for the stabilizing effect of interaction type diversity to emerge in complex communities. The present study indicated that the complexities characterised by species number, connectance, species variation, and interaction type diversity synergistically contributed to maintaining communities, and posed an interesting question of how present complex communities emerged, and developed from simpler ecosystems. [ABSTRACT FROM AUTHOR]

Background There are only a few studies reporting the role of nitric oxide metabolites for controlling macrophage intracellular parasitism, and these are controversial. Therefore, the present study aimed to evaluate the expression of inducible nitric oxide synthase (iNOS) in the lymph nodes and spleen of dogs affected by visceral leishmaniasis through immunohistochemistry and to determine its correlation with tissue parasite burden and serum interferon (IFN)-γ levels. Twenty-eight dogs were selected and assigned to one of two groups, symptomatic (n = 18) and asymptomatic (n = 10), according to clinical status and laboratory evaluation. A negative control group (n = 6) from a non-endemic region for visceral leishmaniasis was included as well. Results Parasite density (amastigotes/mm2) was similar between clinical groups in the lymph nodes (P = 0.2401) and spleen (P = 0.8869). The density of iNOS+ cells was higher in infected dogs compared to controls (P < 0.05), without a significant difference in lymph node (P = 0.3257) and spleen (P = 0.5940) densities between symptomatic and asymptomatic dogs. A positive correlation was found between the number of iNOS+ cells in lymph nodes and interferon-γ levels (r = 0.3776; P = 0.0303), and there was a negative correlation between parasites and iNOS+ cell densities both in lymph nodes (r = -0.5341; P = 0.0034) and spleen (r = -0.4669; P = 0.0329). Conclusion The negative correlation observed between tissue parasitism and the expression of iNOS may be a reflection of NO acting on the control of parasites. [ABSTRACT FROM AUTHOR]

Most organisms interact with multiple mutualistic species that confer different functional benefits, yet current conceptual frameworks do not fully address this complexity. A network approach considers multiple mutualistic interactions within a functional type and has been largely nonmechanistic, with little attention to the fitness consequences of specific interactions. Alternatively, consumer-resource approaches have explicitly characterized the mechanisms and fitness consequences of resource exchange, but have not been extended to functionally divergent partners. First, we merge these approaches using graphical models to define the multiple mutualist effects (MMEs) that occur when a focal species has multiple partner mutualists. This approach mirrors food web research that has been advanced by studies of multiple predator effects as well as by detailed investigations of modules nested within larger networks. Second, we define the pathways through which a focal mutualist and two or more partner species could interact, reviewing examples of MMEs that span a range from positive to negative fitness effects. Third, given the potential for nonadditivity demonstrated by the existing literature, we pose new hypotheses for species-interaction outcomes by examining factors such as the extent of overlap in rewards exchanged among partners and their resulting network topologies. Our synthesis illustrates how the consideration of MMEs can improve the ability to predict the outcomes of losses or gains of mutualisms from ecosystems. [ABSTRACT FROM AUTHOR]

Sexual and parental conflicts can arise because males benefit by inducing elevated reproductive effort in their mates. For females, the costs of such manipulation are often manifested later in life, and may therefore covary with female life expectancy. Here, I outline a simple female life-history model where female life expectancy reflects extrinsic mortality rate, and elevated reproductive effort causes accelerated senescence. Using this model, I show that variation in extrinsic mortality rate can modulate the magnitude and sign of fitness effects that male manipulation has on females. This result has several interesting implications. First, it suggests that the fitness effects of sexual interactions can depend on ecological factors, such as predation, that influence life expectancy. Second, if mortality risk is condition-dependent but reproductive effort is not fully optimized in relation to individual condition, then sexual conflict intensity may increase with individual condition, selecting for condition-dependent reproductive strategies. Third, if males vary in manipulativeness, then the fitness effects of mating with a given male phenotype may depend on both female condition and extrinsic mortality rate. Fourth, life span extension in the laboratory can lead to overestimation of sexual and parental conflicts. Life expectancy may therefore be a key factor in sexual coevolution. [ABSTRACT FROM AUTHOR]

Although microevolution has been shown to play an important role in pairwise antagonistic species interactions, its importance in more complex communities has received little attention. Here, we used two Pseudomonas fluorescens prey bacterial strains ( SBW25 and F113) and Tetrahymena thermophila protist predator to study how rapid evolution affects the structuring of predator-prey communities. Both bacterial strains coexisted in the absence of predation, and F113 was competitively excluded in the presence of both SBW25 and predator during the 24-day experiment, an initially surprising result given that F113 was originally poorer at growing, but more resistant to predation. However, this can be explained by SBW25 evolving greater antipredatory defence with a lower growth cost than F113. These results show that rapid prey evolution can alter the structure of predator-prey communities, having different effects depending on the initial composition of the evolving community. From a more applied perspective, our results suggest that the effectiveness of biocontrol bacteria, such as F113, could be weaker in communities characterized by intense bacterial competition and protist predation. [ABSTRACT FROM AUTHOR]

Abstract: Plant species introduced to new regions can escape their natural enemies but may also lose important mutualists. While mutualistic interactions are often considered too diffuse to limit plant invasion, few studies have quantified the strength of interactions in both the native and introduced ranges, and assessed whether any differences are linked to invasion outcomes. For three Acacia species adapted for ant dispersal (myrmecochory), we quantified seed removal probabilities associated with dispersal and predation in both the native (Australian) and introduced (New Zealand) ranges, predicting lower removal attributable to dispersal in New Zealand due to a relatively depauperate ant fauna. We used the role of the elaiosome to infer myrmecochory, and included treatments to measure vertebrate seed removal, since this may become an important determinant of seed fate in the face of reduced dispersal. We then tested whether differences in seed removal patterns could explain differences in the invasion success of the three Acacia species in New Zealand. Overall seed removal by invertebrates was lower in New Zealand relative to Australia, but the difference in removal between seeds with an elaiosome compared to those without was similar in both countries. This implies that the probability of a removed seed being dispersed by invertebrates was comparable in New Zealand to Australia. The probability of seed removal by vertebrates was similar and low in both countries. Differences in the invasive success of the three Acacia species in New Zealand were not explained by differences in levels of seed predation or the strength of myrmecochorous interactions. These findings suggest that interactions with ground foraging seed predators and dispersers are unlikely to limit the ability of Acacia species to spread in New Zealand, and could not explain their variable invasion success. [Copyright &y& Elsevier]

(a) Direct feeding interactions between a higher predator (the three ‐ spined stickleback, Gasterosteus aculeatus), intermediate consumers (native Mysis salemaai and invasive Hemimysis anomala mysids), and a basal prey (the cladoceran, Daphnia magna). Photo credits: G. aculeatus and H. anomala by Stephen Potts, M. salemaai and D. magna obtained from Wikimedia Commons; (b) functional response of three native mysids (in blue) and three invasive mysids (in red); (c) functional response of three native mysids and one stickleback (in blue) and three invasive mysids and one stickleback (in red). Shaded areas are bootstrapped 95% confidence intervals. Adapted from Barrios ‐ O'Neill et al. (). In Focus: Barrios ‐ O'Neill, D., Dick, J.T.A., Emmerson, M.C., Ricciardi, A., MacIsaac, H.J., Alexander, M.E. & Bovy, H.C. (2014) Fortune favours the bold: a higher predator reduces the impact of a native but not an invasive intermediate predator. Journal of Animal Ecology, 83, 693–701. There is a growing appreciation for the importance of non ‐ consumptive effects in predator–prey interaction research, which can often outweigh the importance of direct feeding. Barrios ‐ O'Neill et al. () report a novel method to characterize such effects by comparing the functional response of native and introduced intermediate consumers in the presence and absence of a higher predator. The invader exhibited stronger direct feeding and was also more resistant to intimidation by the higher predator. This experimental framework may be incorporated into mainstream global change research, for example, to quantify the importance of non ‐ consumptive effects for the success or failure of biological invasions. The article focuses on the paper by Barrios ‐ O'Neill et al. (2014) and in doing so discusses the functional response and non ‐ trophic interaction literature in the context of biological invasions. It also provides a future framework for integrating laboratory experiments, field manipulations and modelling approaches in global change research. [ABSTRACT FROM AUTHOR]

A spatiotemporal discrete predator-prey system is investigated for understanding the pattern self-organization on the route to chaos. The discrete system is modelled by a coupled map lattice and shows advection of populations in space. Based on the conditions of stable stationary states and Hopf bifurcation, Turing pattern formation conditions are determined. As the parameter value is changed, self-organization of diverse patterns and complex phase transition among the patterns on the route to chaos are observed in simulations. Ordered patterns of stripes, bands, circles, and various disordered states are revealed. When we zoom in to observe the pattern transition in smaller and smaller parameter ranges, subtle structures for transition process are found: (1) alternation between self-organized structured patterns and disordered states emerges as the main nonlinear characteristic; (2) when the parameter value varies in the level from 10−3 to 10−4, a cyclic pattern transition process occurs repeatedly; (3) when the parameter value shifts in the level of 10−5 or below, stochastic pattern fluctuation dominates as essential regularity for pattern variations. The results obtained in this research promote comprehending pattern self-organization and pattern transition on the route to chaos in spatiotemporal predator-prey systems. [ABSTRACT FROM AUTHOR]

Brood parasitic birds lay their eggs in other birds' nests, leaving hosts to raise their offspring. To understand parasite-host coevolutionary arms races, many studies have examined host responses to experimentally introduced eggs. However, attending parents often need to be flushed from their nests to add experimental eggs. If these birds witness parasitism events, they may recognize and reject foreign eggs more readily than parents who did not. We found that, after being flushed, female blackbirds, Turdus merula, remained close to their nests. Flushed females were more likely to eject foreign eggs and did so more quickly than females that were not flushed during experimentation. In contrast, flushing did not predict responses and latency to responses to parasitism by song thrush, Turdus philomelos, which flew farther from their nests and likely did not witness experimental parasitism. When statistically considering flushing, previously published conclusions regarding both species' response to experimental parasitism did not change. Nevertheless, we recommend that researchers record and statistically control for whether hosts were flushed prior to experimental parasitism. Our results have broad implications because more vigilant and/or bolder parents can gain more information about parasitism events and therefore have better chances of successfully defending against brood parasitism. [ABSTRACT FROM AUTHOR]