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Interpopulation variation in predator foraging behaviour promotes the evolutionary divergence of prey 总被引：1，自引：0，他引：1
Toju H 《Journal of evolutionary biology》2007,20(4):1544-1553
Despite intensive investigation of the role of predation on evolutionary processes, few studies have questioned the possibility of the evolutionary divergence of prey populations in response to interpopulation variation in predator foraging behaviour. In an interaction between a seed-predatory insect, the camellia weevil (Curculio camelliae), and its host plant, the Japanese camellia (Camellia japonica), I tested whether the evolutionary differentiation of the plant's defensive trait, pericarp thickness, was related to the interpopulation variation in the foraging behaviour of female weevils. I found that the preference of weevils for the plant fruit based on pericarp thickness varied across 13 populations in Japan. Importantly, variation in weevil behaviour explained interpopulation variation in pericarp thickness and the direction/strength of natural selection on the trait. Overall, I show that adaptive foraging of predators can result in the evolutionary divergence of predator-prey interactions. 相似文献
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Documenting trophic niche partitioning and resource use within a community is critical to evaluate underlying mechanisms of coexistence, competition, or predation. Detailed knowledge about foraging is essential as it may influence the vital rates, which, in turn, can affect trophic relationships between species, and population dynamics. The aims of this study were to evaluate resource and trophic niche partitioning in summer/autumn between the endangered Atlantic‐Gaspésie caribou (Rangifer tarandus caribou) population, moose (Alces americanus) and their incidental predators, the black bear (Ursus americanus) and coyote (Canis latrans), and to quantify the extent to which these predators consumed caribou. Bayesian isotopic analysis showed a small overlap in trophic niche for the two sympatric ungulates suggesting a low potential for resource competition. Our results also revealed that caribou occupied a larger isotopic niche area than moose, suggesting a greater diversity of resources used by caribou. Not surprisingly, coyotes consumed mainly deer (Odocoileus virginianus), moose, snowshoe hare (Lepus americanus), and occasionally caribou, while bears consumed mainly vegetation and, to a lesser extent, moose and caribou. As coyotes and bears also feed on plant species, we documented trophic niche overlap between caribou and their predators, as searching for similar resources can force them to use the same habitats and thus increase the encounter rate and, ultimately, mortality risk for caribou. Although the decline in the Gaspésie caribou population is mostly driven by habitat‐mediated predation, we found evidence that the low level of resource competition with moose, added to the shared resources with incidental predators, mainly bears, may contribute to jeopardize the recovery of this endangered caribou population. Highlighting the trophic interaction between species is needed to establish efficient conservation and management strategies to insure the persistence of endangered populations. The comparison of trophic niches of species sharing the same habitat or resources is fundamental to evaluate the mechanisms of coexistence or competition and eventually predict the consequences of ecosystem changes in the community. 相似文献
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Catherine E. Sheppard Richard Inger Robbie A. McDonald Sam Barker Andrew L. Jackson Faye J. Thompson Emma I. K. Vitikainen Michael A. Cant Harry H. Marshall 《Ecology letters》2018,21(5):665-673
Individual foraging specialisation has important ecological implications, but its causes in group‐living species are unclear. One of the major consequences of group living is increased intragroup competition for resources. Foraging theory predicts that with increased competition, individuals should add new prey items to their diet, widening their foraging niche (‘optimal foraging hypothesis’). However, classic competition theory suggests the opposite: that increased competition leads to niche partitioning and greater individual foraging specialisation (‘niche partitioning hypothesis’). We tested these opposing predictions in wild, group‐living banded mongooses (Mungos mungo), using stable isotope analysis of banded mongoose whiskers to quantify individual and group foraging niche. Individual foraging niche size declined with increasing group size, despite all groups having a similar overall niche size. Our findings support the prediction that competition promotes niche partitioning within social groups and suggest that individual foraging specialisation may play an important role in the formation of stable social groupings. 相似文献
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1. Mating and foraging are generally mutually exclusive activities. Individuals are thus faced with a continuous trade-off between time and energy expended in foraging and mating, but different phenotypes should respond to this trade-off in different ways. 2. Sexual selection theory predicts that females should maximize their time and energy spent gathering resources, whereas males should maximize their time and energy spent obtaining mates, thus minimizing their time spent foraging, subject to the constraint that they need to forage minimally to sustain their activity. 3. Smaller individuals require less food to maintain their activity. Small males in particular could therefore increase mating effort at the expense of foraging effort and, all else being equal, may thus enjoy a time budget advantage relative to large males. On the other hand, larger individuals may compensate by being more efficient at finding prey and/or extracting nutrients. 4. The effects of sex, body size, and prey density on foraging time budgets of male and female yellow dung flies, Scathophaga stercoraria, were investigated in the laboratory. 5. Higher prey density (Drosophila melanogaster) resulted in reduced feeding (= handling) and hunting (= waiting or search) times for both sexes, as predicted by the marginal value theorem applied to foraging theory. Females fed longer on a prey item than did males, and also caught the next prey item more quickly. Large individuals extracted nutrients more quickly, but were not faster at catching prey. Small individuals satiated more quickly than larger individuals and also ate fewer prey items. 6. These results are largely consistent with the predictions and suggest a small-male time budget advantage in the yellow dung fly. Integrating the various predictions to test directly for a small-male time budget advantage is difficult in the laboratory, however, because hunting times are unlikely to reflect the natural situation. To what extent these results lead to increased probabilities for small males of obtaining matings in the field remains to be demonstrated. 相似文献
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J. F. HUSAK† 《Functional ecology》2006,20(1):174-179
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An ecological niche has been defined as an n‐dimensional hypervolume formed by conditions and resources that species need to survive, grow, and reproduce. In practice, such niche dimensions are measurable and describe how species share resources, which has been thought to be a crucial mechanism for coexistence and a major driver of broad biodiversity patterns. Here, we investigate resource partitioning and trophic interactions of three sympatric, phylogenetically related and morphologically similar species of thrushes (Turdus spp.). Based on one year of data collected in southern Brazil, we investigated niche partitioning using three approaches: diet and trophic niche assessed by fecal analysis, diet and niche estimated by stable isotopes in blood and mixing models, and bipartite network analysis derived from direct diet and mixing model outputs. Approaches revealed that the three sympatric thrushes are generalists that feed on similar diets, demonstrating high niche overlap. Fruits from C3 plants were one of the most important food items in their networks, with wide links connecting the three thrush species. Turdus amaurochalinus and T. albicollis had the greatest trophic and isotopic niche overlap, with 90% and 20% overlap, respectively. There was partitioning of key resources between these two species, with a shared preference for fig tree fruits—Ficus cestrifolia (T. amaurochalinus PSIRI% = 11.3 and T. albicollis = 11.5), which was not present in the diet of T. rufiventris. Results added a new approach to the network analysis based on values from the stable isotope mixing models, allowing comparisons between traditional dietary analysis and diet inferred by isotopic mixing models, which reflects food items effectively assimilated in consumer tissues. Both are visualized in bipartite networks and show food‐consumers link strengths. This approach could be useful to other studies using stable isotopes coupled to network analysis, particularly useful in sympatric species with similar niches. 相似文献
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Historical biases towards the study of Palearctic and Nearctic bird migration systems has resulted in a dearth of information on the ecology of intratropical migrants, which likely also play important ecological roles within their communities. For instance, there is little information on the foraging ecology and breeding biology of co‐occurring migrants and residents within the intratropical migratory system. Thus, we used two congeneric flycatchers – the resident Plain‐crested Elaenia Elaenia cristata (Aves: Tyrannidae), and the migrant Lesser Elaenia E. chiriquensis (Tyrannidae) – to check whether either of them showed foraging niche plasticity mediating their coexistence and the effects of such syntopy on their breeding behavior and fitness. To do so, we used an ensemble of methods that included the evaluation of food resource phenology, foraging behavior observations, stable isotope ratio analysis in birds’ tissues, and nest monitoring. Our results confirmed that residents have foraging behavior plasticity but reveals its trophic behavior and breeding success is independent of the coexistence with migrants. Since such results depart from the predictions based on the current (and often Northern‐biased) theories of bird migration, we discuss alternative hypotheses explaining our findings, including the influence of physiology on diet and the behavioral responses of nest predators. Once there is a clear knowledge gap about the interspecific interactions between residents and intratropical migrants, our study represents a simple, yet important, step towards understanding the mechanisms underlying this system. 相似文献
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- Anadromous fishes can be important prey resources for piscivorous fauna in lowland rivers. Freshwater anglers exploiting large‐bodied cypriniform fishes use high quantities of pelletised marine fishmeal baits that can contribute substantially to fish diets. This marine‐derived energy pathway also potentially provides a marine prey resource for freshwater piscivores. However, large‐bodied cypriniform fishes are often in a size refuge against predation due to their large sizes.
- Stable isotope (δ15N and δ13C) analysis assessed how novel marine prey resources influenced the diet of a freshwater apex predator, northern pike Esox lucius, in an impounded river basin (lower River Severn, western England). Up to three groups of prey resources were present: anadromous European shad (Alosa spp.), cypriniform fishes with dietary specialisms based on marine fishmeal baits, and freshwater prey. The availability of these prey resources to E. lucius varied according to river connectivity and levels of angling exploitation in different river reaches.
- Where the three prey groups were present, E. lucius were more enriched in δ13C values (range: ?24.74 to ?16.34‰) compared to river reaches where aspects of the marine prey groups were absent (range: ?28.30 to ?21.47). In all reaches, δ13C increased as E. lucius length increased. In the reach where all prey groups were present, the isotopic niches of three E. lucius size categories were strongly partitioned; this was not apparent in reaches where the marine pathways were unavailable.
- Stable isotope mixing models suggested that freshwater prey were the most important prey item, contributing between 42% and 96% to the diet of individual E. lucius. However, where present, anadromous fishes and cypriniform fishes specialising on marine fishmeal baits were also important prey items, contributing substantially to the diet of larger E. lucius (length > 650 mm). The total dietary contributions of the marine resources varied considerably among the individual larger fish (22–58% of total diet).
- The presence of two marine resource pathways in a lowland river thus strongly influenced the diet of an apex predator, but with contributions being a function of their spatial availability, E. lucius body size and individual trophic specialisations. These results emphasise how the anthropogenic activities of river engineering and human subsidies can affect the trophic dynamics of apex predators.
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Christina Skinner Aileen C. Mill Steven P. Newman Jason Newton Matthew R. D. Cobain Nicholas V. C. Polunin 《Ecology and evolution》2019,9(23):13267-13277
Sympatric species may partition resources to reduce competition and facilitate co‐existence. While spatial variation and specialization in feeding strategies may be prevalent among large marine predators, studies have focussed on sharks, birds, and marine mammals. We consider for the first time the isotopic niche partitioning of co‐occurring, teleost reef predators spanning multiple families. Using a novel tri‐isotope ellipsoid approach, we investigate the feeding strategies of seven of these species across an atoll seascape in the Maldives. We demonstrate substantial spatial variation in resource use of all predator populations. Furthermore, within each area, there was evidence of intraspecific variation in feeding behaviors that could not wholly be attributed to individual body size. Assessing species at the population level will mask these intraspecific differences in resource use. Knowledge of resource use is important for predicting how species will respond to environmental change and spatial variation should be considered when investigating trophic diversity. 相似文献
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Alternative forms of competition and predation dramatically affect habitat selection under foraging--predation-risk trade-offs 总被引：3，自引：0，他引：3
Habitat selection under foraging—predation-risk trade-offshas been a frequent topic of interest to theoretical behavioraland evolutionary ecologists. However, most habitat selectionmodels assume that individuals compete exploitatively for resourcesand that predation is either density independent or dilutedcompletely by competitor number, despite empirical evidencethat other forms of competition and predation also occur innature. I developed an individual-based model for studyingthe effects of alternative forms of competition and predationon the process of habitat selection under foraging—predation-risktrade-offs. To make the model more relevant to natural populations,I assumed that individuals vary continuously in traits relatedto competitive ability and vulnerability to predation and allowedresources and predators to be distributed across more than twohabitats. The results of my investigation demonstrate thatthe predicted pattern of habitat selection can be affecteddramatically by the form predation is assumed to take. Whenpredation is density dependent or frequency dependent, individualswill tend to be distributed across habitats according to theirabsolute vulnerability to predation. In contrast, when predationis density dependent or vulnerability dependent, individualswill tend to segregate by competitive ability. Whether oneassumes that individuals compete for resources via exploitationor interference also influences the predicted pattern of habitatselection. In general, interference competition results in amore even distribution of competitors across habitats. 相似文献
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We investigate the optimal behaviour of an organism that is unable to obtain a reliable estimate of its mortality risk. In this case, natural selection will shape behaviour to be approximately optimal given the probability distribution of mortality risks in possible environments that the organism and its ancestors encountered. The mean of this distribution is the average mortality risk experienced by a randomly selected member of the species. We show that if an organism does not know the exact mortality risk, it should act as if the risk is less than the mean risk. This can be viewed as being optimistic. We argue that this effect is likely to be general. 相似文献
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Introduced and allopatric populations of brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss were sampled in Slovenia for stable isotope analysis to assess dietary niche shifts through ontogeny and estimate the propensity for cannibalism. Both S. trutta and O. mykiss are cannibals, with higher average relative contribution of conspecific assimilated energy for S. trutta (27·9%) compared with O. mykiss (7·7%). The smallest cannibal was 166 mm in the S. trutta population and 247 mm in the O. mykiss population. 相似文献
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1. Co‐occurrence of closely related predators in a prey‐limited habitat appears to contradict the principle of competitive exclusion, however it may be explained through indirect effects, niche shifts, and intraguild predation. 2. The interactions between sympatric tiger beetle Cicindela species were examined. Cicindela circumpicta is the largest of three species (C. circumpicta, C. togata, C. fulgida) found in saline habitats throughout central North America. The temporal occurrence of these species overlaps, as does their spatial occurrence on exposed salt flats of saline marshes. During field observations, exoskeletal remains of C. togata were found at the study site in Nebraska, U.S.A. 3. In laboratory trials, male C. circumpicta ate C. togata in 38% of trials and female C. circumpicta ate C. togata in 50% of trials (n = 24). 4. In the field, potential prey, consisting mainly of small flies, was found mostly in shaded conditions but tiger beetles differed significantly in shade use, with C. circumpicta spending 70% of the time in the shade compared with ≈ 20% for C. togata. Differential habitat use was not explained by maximum temperature tolerances, which did not differ between the species. 5. Laboratory trials established that both tiger beetle species consumed small prey (apterous Drosophila) but C. togata was more efficient at capturing winged Drosophila. 6. Foraging efficiency, as measured by the time taken for a C. togata to capture three prey items, decreased significantly in the presence of other tiger beetles, especially C. circumpicta. 7. These results are an indication that intraguild predation and induced changes in foraging behaviour operate in the ecology of adult tiger beetles. 相似文献
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Bruno R. S. Figueiredo Roger P. Mormul Ben B. Chapman Lucas A. Lolis Leandro F. Fiori Evanilde Benedito 《Freshwater Biology》2016,61(3):293-300
- In aquatic systems, many species rely primarily on visual cues to choose optimal foraging sites, capture prey and avoid potential threats. Increases in the turbidity of water reduce visibility and impede animals in determining the precise location of both predators and food. How individuals balance foraging decisions with anti‐predator behaviour in turbid environments is not well understood.
- We tested the effects of turbidity and predation risk on the foraging behaviour and feeding of an invertivorous fish, Moenkhausia forestii (Characidae), using a mesocosm experiment with a 2 × 2 design, crossing water clarity (clear versus turbid) with predation risk as reflected by the presence or absence of the piscivorous wolf‐fish Hoplias aff. malabaricus (Erythrinidae). We predicted that turbidity and predator presence would interact additively to reduce foraging rates, and that increased turbidity or predator presence would result in disproportionate food partitioning among shoal members.
- The combination of high turbidity and predator presence resulted in a significant reduction in prey consumption. Foraging success exhibited a skewed distribution in the turbid treatment, i.e. there was a decreased evenness of food partitioning within shoals. Hence, both turbidity and predator presence affect the prey consumption and foraging behaviour of invertivorous fish, with turbidity amplifying the non‐lethal effects of predation risk on foraging success.
- Our results imply that turbidity‐induced visual obstruction amplifies the negative effects of predator presence on invertivorous fish feeding behaviour, resulting in higher prey survival. Also, our finding that food intake by an intermediate consumer decreased in turbid water with a top predator lends no support to the hypothesis that intermediate consumer fish reduce their anti‐predator behaviour in turbid water.
- From a management perspective, our findings suggest that the oligotrophication of aquatic systems could dramatically increase predation on basal prey organisms naturally adapted to turbid waters, and reduce within‐shoal differences in feeding behaviour.
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Field and laboratory experiments were set up to obtain data on the reasons for different habitat selection of Enallagma cyathigerum and Platycnemis pennipes. (1) Rearing of larvae in two different ponds showed that while P. pennipes was not able to survive conditions of low oxygen content, 50% of the E. cyathigerum larvae survived. (2) In field predation experiments with sticklebacks and dragonflies as predators, we found that E. cyathigerum suffered highest predation by the fish. In P. pennipes, mortality was highest with Anax imperator. (3) Experiments regarding larval behaviour showed that E. cyathigerum was generally more active and had higher foraging success than P. pennipes. Both species reduced activity in the presence of fish, but E. cyathigerum did so to a minor extent. In contrast to P. pennipes, E. cyathigerum showed escaping behaviour. (4) In the laboratory, the growth of E. cyathigerum was faster than that of P. pennipes. 相似文献
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Starry flounder Platichthys stellatus , a rare polymorphic flatfish exhibiting a large-scale geographic cline in the frequency of right-eyed (dextral) and left-eyed (sinistral) morphs, was studied to investigate whether foraging behaviour (turning angle and prey strike orientation) differed between dextral and sinistral laboratory-raised juveniles. Platichthys stellatus foraging on brine shrimp Artemia sp. nauplii tended to strike dorsally at prey ('left' to an observer for dextral flounder and 'right' to an observer for sinistral flounder), although this effect was stronger for sinistral fish. This dorsal tendency also increased with body size. Non-strike behaviours (movements between strikes) were ventrally biased for both morphs. Maximum turn angles were larger for both morphs towards the dorsal side than the ventral side during prey strikes but were the same during non-strike behaviours. The positioning of the eyes of the juvenile starry flounder was skewed towards the dorsal midline rather than being symmetrically placed between dorsal and ventral margins on the eyed side of each fish. The migrating eyes of dextral fish, however, were significantly closer to the dorsal midline than in sinistral fish. This, in addition to the more dorsally oriented prey strikes in sinistral fish, suggests that the morphs are not simple behavioural mirror images of one another and therefore may differ ecologically. 相似文献