Coexisting species are often assumed to reduce competition by foraging for foods that differ in nutrient composition, but few studies test whether field nutritional differences correspond to intrinsic differences in macronutrient selectivity. We compared field estimates of worker trophic position (tissue isotopes: δ 15 N) and worker tissue stoichiometry (elemental ratios: C:N) among 17 co‐occurring Australian ant species with laboratory protein:carbohydrate intake targets (P:C ITs), measured in brood‐free worker groups under competition‐free, standardised conditions. Field‐collected ants differed strongly in trophic and stoichiometric signatures – worker δ 15 N spanned 7.1‰ among species and C:N varied 1.33‐fold. In contrast, laboratory P:C ITs were comparatively overlapping (mean 1.00 ± 0.06 SE; range 0.60–1.42). Lab P:C ITs did not predict species‐mean δ 15 N or C:N (H1); pairwise coupling between lab P:C IT and field metrics was weak at best (~ 5% variance; H2), and residual/compensatory divergence was unsupported (H3). Synthesis – these results show that co‐occurring ant species can differ markedly in field trophic position and worker stoichiometry despite overlapping lab‐measured macronutrient intake selectivity. This lab–field decoupling is consistent with extrinsic ecological constraints on realised nutritional outcomes, but the mechanisms generating these differences, including any role in coexistence, were not directly tested here.
Tipping points (TPs) – often understood as abrupt changes to a system – have become a popular framework for ecology and environmental science across spatial and temporal scales. The underlying, quantitative foundation of TP theory is built on mathematical models from catastrophe and predator–prey theories. Tipping points based on a cusp catastrophe model were critiqued early, but that history did not happen for TPs derived from predator–prey theory. Here we summarize both histories and resulting flaws in the understanding and application of TPs. Unfortunately, much of what has been written about TPs is derived from predator–prey theory and is not readily defended: multiple assumptions cannot apply; other problems exist; and evidence is weak or lacking. Fortunately, early critique led to a viable approach to evaluate TPs based on the cusp catastrophe model. We suggest TPs based on predator–prey theory be abandoned and many putative TPs be re‐assessed with modern tools based on the cusp catastrophe model and/or other potential approaches. Tipping points may then be useful to understand changing systems if other important problems (publication bias, lack of empirical evidence, stability concepts, scale) can also be surmounted. In the meantime, the science of TPs lags far behind the concept's popularity, and so TPs are not yet a solid foundation for environmental policies.
Understanding how ecosystems retain or release carbon under warming is a critical challenge. Dominant plant species, which contribute the most biomass, can mediate ecosystem responses to warming by modifying microclimate and nutrient cycling. To investigate how warming and shifts in plant dominance interact to affect carbon and nutrient dynamics, we conducted a decade‐long field experiment combining in situ warming and dominant species removal at a low‐ and at a high‐elevation montane meadow site. We hypothesized that warming would enhance plant productivity and soil nutrient availability by altering microclimate conditions, which would then lead to shifts in soil carbon. Warming increased soil temperature most strongly at the high‐elevation site, though soil moisture responses to warming were limited at both elevations. Species removal reduced plant biomass more strongly at the low‐elevation site, though the most pronounced differences in microclimate, biomass, and soil properties occurred between elevations. While warming reduced potential mineralization rates and removal increased total soil nitrogen, warming and removal had limited effects on total soil carbon (C). However, they significantly altered the composition of soil organic matter, shifting the balance between plant‐ and microbial‐derived compounds. These findings suggest that even in the absence of changes to bulk C pools, warming and vegetation change can influence long‐term soil carbon stability by modifying the quality of organic matter and thus its physicochemical properties and decomposability. Our results highlight the importance of dominant species and elevation context in shaping belowground responses to climate change, driving shifts in microclimate, vegetation composition, and carbon pools that may influence soil carbon stability and ecosystem resilience.
Island biogeography theory predicts that island plants should exhibit reduced defences compared with their mainland relatives due to relaxed herbivory pressure. However, growing empirical evidence challenges this prediction, revealing substantial variation among systems, plant lineages and defence types. These inconsistencies suggest that simple expectations of reduced defence on islands overlook the diversity of selective agents and strategies plants use to cope with herbivores. A more integrative perspective proposes that island – mainland comparisons should simultaneously consider multiple defensive mechanisms, including resistance – both constitutive and inducible – and tolerance‐related traits. In this study, we conducted two complementary greenhouse experiments to examine resistance and tolerance responses in seven island–mainland species pairs of oaks Quercus across three biogeographical regions: Bornholm Island versus mainland Sweden, the Balearic Islands versus mainland Spain, and Lesbos Island versus mainland Greece. Seedlings were exposed to controlled foliar herbivory by the generalist Lymantria dispar , with undamaged plants serving as controls. Resistance was quantified by measuring key chemical defences – namely total phenolic content and volatile organic compounds – assessed both at constitutive levels and in terms of inducibility following herbivore damage. Tolerance, in contrast, was evaluated as the plant's capacity for growth compensation, quantified through height regrowth after herbivory. Our results show that, contrary to traditional expectations, island and mainland oak seedlings did not differ significantly in either chemical resistance or growth‐based tolerance to herbivory. These results suggest that the evolution of plant defences on islands may not be universally reduced and that both island and mainland oaks maintain comparable strategies to cope with herbivory, highlighting the importance of considering multiple defence mechanisms and local ecological contexts when assessing insularity effects.
Shared flowers can facilitate pathogen transmission between managed honey bees and wild bees, yet this process remains poorly understood in ecosystems undergoing rapid environmental change. Using a glacier foreland in Switzerland, we present the first study on how glacier retreat stages and bee life‐history traits influence pathogen occurrence across honey bees and wild bees. We screened the deformed wing (DWV), acute bee paralysis (ABPV), chronic bee paralysis (CBPV) viruses, the microsporidium Nosema ceranae , and the trypanosomatid Lotmaria passim . While all screened pathogens were detected in honey bees, only N. ceranae and DWV occurred in wild bees, though DWV strains differed between hosts (A in wild bees, B in honey bees). This clear segregation of pathogen communities between honey bees and wild bees is likely explained by the different floral resources used bythe two bee groups, overall forming a moderately specialised and not nested network with honey bees especially targeting few plant species rarely visited by wild bees. Sociality and nesting habits did not explain pathogen loads, whereas glacier retreat stage significantly influenced DWV abundance, with higher loads in older successional stages. This case study provides a fascinating example of how the use of floral resources by honey bees and wild bees, alongside the landscape changes induced by glacier retreat, can greatly influence pathogen transmission dynamics.
The origins of ecosystem stability have long intrigued ecologists. Recent theoretical advancements highlight three primary mechanisms driving stability: dominance, asynchrony and averaging. While plant community stability has been extensively studied, our understanding of marine community stability remains limited. Plankton, as key components of marine ecosystems, play vital roles in carbon and nutrient cycling as well as climate regulation. Identifying the drivers of plankton community stability is therefore essential for effective ecosystem management and conservation. Using a biogeochemical model that realistically represents plankton biodiversity, we identified dominance and averaging as the main mechanisms driving plankton community stability. By studying plankton communities across different temporal, spatial and trophic scales, we were able to show that changes in these dimensions can alter the dominant stabilizing mechanism. Stronger stabilization arising from dominance was linked to reduced biomass evenness, while stronger stabilization through averaging was linked to increased biomass evenness. Understanding the mechanisms that underpin the stability of plankton communities is essential to anticipate how marine ecosystems will respond to environmental change and which types of disturbances most threaten plankton communities. If stability is primarily driven by dominance, the system may appear stable but remain highly vulnerable, as its balance relies on a few functional groups. In contrast, when stability arises from temporal asynchrony or the averaging effect among many groups, the community can better buffer environmental fluctuations but becomes more sensitive to biodiversity loss.
Individuals that disperse typically exhibit specific phenotypical traits that facilitate dispersal and settlement success, known as 'dispersal syndromes'. Consequentially, characterizing dispersers is crucial to understand other processes such as metapopulation dynamics and biological invasions. One trait that may play a major, yet overlooked, role in dispersal is relative brain size. Larger brains, through enhanced cognition and behavioural flexibility, could both increase and decrease the costs of dispersal, depending on the ecological context. However, barely any effort has been made to investigate the link between brain size and dispersal, especially so at the individual level. Here, we tested the impact of brain size on dispersal behaviour, in both a stable and unpredictable environment. We used Trinidadian guppies Poecilia reticulata from lines artificially bred for large and small relative brain size. Fish were placed in a laboratory set-up of interconnected tanks, where we quantified how likely and how fast they were to disperse between tanks under two ecologically relevant conditions: a stable (control) and unpredictable environment (experimental drought). Surprisingly, there was only limited evidence that large- and small-brained guppies differed in dispersal behaviour in either ecological context. While we found no differences in dispersal behaviour between the large- and small-brained lines, both overall dispersal speed and dispersal likelihood correlated negatively with individual relative brain size, but only during the first opportunity fish had to disperse. Generally, guppies reduced dispersal after experiencing an environmental drought. Regardless of brain size or ecological context, they exhibited consistent interindividual variation in their decision to disperse or to stay, indicating the existence of a dispersal personality trait. Our results are valuable in the current context of invasive alien species. Understanding what traits influence the success during the various steps of the invasion process is of major importance from both a fundamental and conservation perspective.
Niche partitioning is important for the coexistence of closely related species, allowing species to reduce overlap in resource use despite shared ecological requirements. In alpine environments, harsh climatic conditions and low habitat complexity constrain opportunities for ecological segregation, making seasonal resource fluctuation especially important for maintaining coexistence. Under such conditions, both historical niche divergence and flexible responses to changing resources are likely to shape the existing patterns of dietary overlap. Here, we examined seasonal dietary niche partitioning between two sympatric herbivorous birds, willow ptarmigan Lagopus lagopus and rock ptarmigan L. muta during the winter-spring transition over six years in central Norway. Using DNA metabarcoding (ITS) of 400 fecal samples, we characterized plant diets and examined interspecific differences in composition, seasonal shift, niche breadth and overlap. There was strong evidence for dietary differentiation between species and across seasons, with species-specific seasonal shifts in plant occurrence. During winter, partitioning was mostly quantitative with both species relying on birch Betula sp., but rock ptarmigan also heavily utilized crowberry Empetrum nigrum. In spring, dietary richness and divergence increased, driven by an expansion of niche breadth in willow ptarmigan towards emerging bilberry Vaccinium myrtillus. In contrast, rock ptarmigan appeared to maintain a relatively stable and specialized niche, while increasing the use of alpine heaths. However, analyses at wider spatial scales may reveal different patterns. We demonstrate that fine-scale partitioning of shared resources can structure dietary niches in sympatric alpine herbivores and that seasonal divergence is mainly driven by shifts in the relative use of shared taxa rather than complete turnover in diet composition. These findings suggest that coexistence in a low-productivity alpine system may depend on persistent specialization and seasonal flexibility of both ptarmigan species. We suggest that ongoing changes in alpine vegetation, such as shrub encroachment, may alter resource overlap and reshape niche boundaries.
Understanding how different drivers of global change interact to shape ecological processes remains a major challenge in ecology. Climate change is reshuffling the interactions that structure communities, with major implications for biological invasions. A key consequence of such reshuffling is the alteration of biotic resistance through changes in antagonistic interactions such as post-dispersal seed predation. This process is highly context dependent and influenced by factors such as climate and microhabitat. However, how large- and local-scale factors interact to shape seed predation remains poorly understood. In this study, we conducted a seed removal experiment along a precipitation gradient in Patagonia, Argentina, to evaluate whether a large-scale factor, precipitation, interacts with a local-scale factor, microhabitat type (open or closed vegetation), to influence seed predation patterns of a non-native conifer species Pinus ponderosa. By measuring seed predation at 960 depots across 12 precipitation levels, we found that seed predation changed across the precipitation gradient and tended to be higher in open habitats at lower precipitation and in closed habitats at higher precipitation. However, this pattern was contingent on temporal context, indicating shifts in granivore activity. These findings suggest that any potential contribution of seed predation to biotic resistance is jointly determined by the interaction between climatic conditions, local habitat structure, and temporal contexts. Together, these results highlight the importance of accounting for multiple interacting factors to better understand and predict seed predation of non-native species under changing environmental conditions.
In tropical forests, habitat loss reshapes species composition, favoring generalists and recently emerged lineages while specialists and older evolutionary lineages are lost. However, how changes in species ecological attributes and evolutionary history affect ecological processes is poorly explored. Using the well-known frugivory system of Euterpe edulis, an emblematic palm species of the Atlantic Forest, and its avian frugivores, we investigated how habitat loss influenced both ecological and evolutionary history across 150 forest remnants within the palm's potential distribution. We inferred potential interactions using a co-occurrence approach based on the overlap between palm suitability and bird occurrences. We hypothesized that landscape-scale forest loss negatively affects the ecological and evolutionary dimensions of the network, leading to declines in functional, phylogenetic and evolutionary distinctness of interactions. Consistent with this hypothesis and supported by validation using 21 field studies, we showed that forest loss reduces the diversity of birds that interact with Euterpe edulis, including those with distinct evolutionary histories. We showed that each 1% forest loss reduces 50 000 years of evolutionary distinct interactions, while phylogenetic and functional diversity also decline. Specifically, frugivores with large gape size and those that forage in mid-high and canopy strata are negatively affected, whereas ground-foraging species are positively affected. These shifts likely reduce the quality of seed dispersal and may compromise plant recruitment. Thus, habitat loss not only simplifies interaction networks but also erodes a key mutualism by selectively eliminating functionally and phylogenetically important partners of E. edulis.
Nutrients, including vital organic compounds, vary in availability across ecosystems, with the potential to act as a source of selection for traits that increase nutrient acquisition and biosynthesis. Compared to freshwaters, marine ecosystems are richer in the omega-3 long-chain polyunsaturated fatty acid (n-3 LC-PUFA) docosahexaenoic acid (DHA). Dietary and metabolic changes during the freshwater establishment process have likely helped ancestrally-marine fish survive the challenges of freshwater nutritional environments. We explored both genotypic and phenotypic variation among threespine stickleback Gasterosteus aculeatus populations that vary in their history of freshwater establishment and in the nutritional availability of contemporary resources. Specifically, we examined how fads2 copy number, a gene associated with fatty acid synthesis, as well as the fatty acid content of fish and their prey, varies among populations. We found evidence that multiple freshwater stickleback populations have fads2 copy number duplications. Stickleback prey varied in their fatty acid composition across major taxonomic groups and in their relative availability across sites. Diet variation among stickleback populations reflected the relative availability of local prey. However, stickleback DHA phenotypes were remarkably similar across populations, despite wide variation in both fads2 copy numbers and diet. While contents of eicosapentaenoic acid (EPA), another n-3 LC-PUFA, were also conserved in muscle tissue of sticklebacks across populations, the contents of other fatty acids varied widely across populations, suggesting that other fatty acids are under less strict metabolic control and reflect more local variation across the landscape. Overall, our results suggest that in spite of genetic variation in synthesis capacity, sticklebacks are able to acquire n-3 LC-PUFA across freshwaters. They do appear to do so while consuming a diversity of nutritionally-variable prey. Future studies should aim to help reveal the rates at which traits related to foraging versus those related to metabolism evolve in response to the nutritional landscape.
Understanding the distribution patterns of species richness and their underlying drivers is a fundamental issue in macroecology and biogeography. While climate, soil, topography and human activities are widely recognized as key determinants, their interactive effects on species richness patterns remain underexplored, especially for ecologically and economically valuable Pinus species. Furthermore, the role of indirect effects among variables in shaping these patterns remains incompletely clarified. Here, we integrated distribution data for 60 North American Pinus species to investigate richness patterns across different range sizes. Using structural equation modeling (SEM), we quantified the relative explanatory power of hypotheses related to environmental and anthropogenic factors. We also identified diversity hotspots using the complementary algorithm and the top 5% richness approach. Our results show that topographical heterogeneity is the primary direct correlative factor explaining richness patterns for overall species. Human activities are the dominant correlative factor for both overall and wide-ranged species: their total effect on overall species is primarily derived from indirect associations through modified environmental conditions, while they exert the strongest direct effect on wide-ranged species. The Janzen hypothesis better explains the richness patterns of narrow-ranged species, emphasizing the importance of climatic stability and habitat specificity. Additionally, the complementary algorithm outperformed the top 5% richness approach in identifying priority conservation areas by efficiently capturing all species. This study elucidates the divergent associative mechanisms shaping Pinus species richness across different range sizes, highlighting that human activities and topographical heterogeneity play context-dependent roles. These findings enhance our understanding of the multi-faceted mechanisms influencing Pinus species richness patterns and provide a targeted scientific basis for biodiversity conservation planning and adaptive management strategies under global climate change.
Climatic conditions shape phenotypic evolution by driving adaptations that optimise organismal function. Invasive species provide valuable systems to study these processes, as they often encounter novel climatic conditions in their introduced ranges. The European rabbit Oryctolagus cuniculus , native to the Iberian Peninsula, has established populations across Europe and Australia, where climatic conditions differ markedly. We examined how temperature, aridity, and precipitation jointly influence cranial morphology across native and invasive populations. Australia is generally warmer and more arid than European locations and we found that rabbits from Australia exhibited larger overall body size. Climate appears to shape morphological diversity differently in introduced versus native ranges by leveraging changes to trait allometry. Climate alone was found to be not as influential on rabbit morphology in the introduced range as it is in Europe. These findings demonstrate that a mosaic effect of different climatic factors shapes morphological evolution, particularly for invasive species adapting to novel ecological conditions. Furthermore, we suggest that allometry could potentially act as a mechanism to generate change in individual traits when animals are introduced to novel habitats, although the factors responsible for driving body size in rabbits of Australia remain to be understood.
Predator-prey interactions are key ecological processes structuring wildlife communities by shaping species abundances and distributions, thereby influencing ecosystem functioning. They result from the interplay of bottom-up (e.g. prey availability) and top-down (e.g. predator control) forces. By altering species diversity and behaviors, humans can reshape trophic structures and predator-prey relationships. In Central African forests, where leopards Panthera pardus and African golden cats Caracal aurata are the largest carnivores, we examined trophic structure, spatiotemporal predator-prey dynamics, and responses to human presence and hunting pressure, a largely understudied issue. We hypothesized that increasing human pressure alters community structure and trophic organization, consistent with trophic downgrading and the view of humans as 'super predators'. Using camera trap data from three sites along a human pressure gradient in the Republic of Congo and Cameroon, we tested two predictions: (P1) in low-pressure forests, functional diversity is higher and predator-prey dynamics are shaped by ecologically-driven bottom-up and top-down processes; (P2) in high-pressure forests, humans exert top-down control across multiple trophic levels, reducing functional diversity and disrupting spatiotemporal predator-prey relationships. Combining community diversity analyses, structural equation modeling, and diel activity analyses, we found patterns consistent with both predictions. In low-pressure areas, prey availability and predator presence jointly structured spatiotemporal patterns, supporting functionally rich communities. Conversely, in the most disturbed area with higher human density and intense hunting, both focal predators were absent, ungulate detections declined by 41-89%, and small generalists became up to 23 times more common than in undisturbed areas. Prey spatiotemporal patterns also shifted, reflecting human avoidance. These findings suggest that humans can act as 'super predators' in Central African forests, overriding natural predator-prey spatiotemporal organization and disproportionately altering mammal communities. Together, our results indicate that limiting hunting pressure across large, connected landscapes appears critical for maintaining trophic network integrity and ecosystem functioning.
Tree invasions threaten native forests worldwide, yet little is known about how to prevent this process. To detect these invasions early it is vital to anticipate potential invaders: identifying traits of successful tree invaders in forests is key. The Pinaceae family is an ideal study system to identify which traits favor tree invasions in forests because many of its species were planted in forests across the world several decades ago and they include many plant traits potentially associated with invasion success. For 45 introduced Pinaceae species planted 100 years ago on an island dominated by native forests in Patagonia, and for the subset of 24 species naturalized on this island, we evaluated the relationship between traits (seed mass, maximum height, wood density, juvenile period and interval between large seed crops) and invasion incidence (whether a species has become invasive or not) or extent (number of invaded transects across the study area). We found that invasion incidence and extent increased with maximum height, decreased with seed mass, juvenile period, and interval between large seed crops, and was unaffected by wood density. These results were similar for both introduced and naturalized species pools. Taller trees with smaller seeds, which start producing seeds earlier and continuously, will produce more seeds that can disperse further (especially if released from greater heights), increasing the probability of finding suitable microsites for seedling establishment, and accelerating population spread. In this study system, we conclude that future introductions of non-native tree species to forests should focus on species with lower invasion risk: those with lower maximum height, bigger seeds, longer juvenile periods, and longer intervals between large seed crops.
We tested the hypothesis that both density- and frequency-dependent interactions play important roles in determining plant growth in a dune heath ecosystem at several levels of available nitrogen. Plant growth was measured using the pin-point method in a five-block experiment with four nitrogen levels. To maximize statistical power, we used only three taxonomic groups: Calluna vulgaris, Avenella flexuosa (the two most dominant species), and all other vascular plant species together. The results show that both Lotka-Volterra type interspecific competition and frequency-dependency play significant roles in determining the growth of the species in the community. Significant interspecific density-dependent competition was observed in four out of the six possible cases. Nitrogen addition increased the competitive effect of C. vulgaris on the growth of the other species. Both C. vulgaris and A. flexuosa showed frequency-dependent positive feedback dynamics on growth when they were relatively dominant at the plot scale, and this effect increased with added nitrogen. In plots with added nitrogen, the group of other species benefited from being relatively rare. The study highlights the importance of the combined effects of density and frequency dependency in determining plant growth.
Hesse's rule posits that animals living in cold environments have larger heart size compared to closely related species inhabiting warmer regions. However, evidence for this pattern in birds remains limited, and a comprehensive cross-species examination is still lacking. In this study, we tested Hesse's rule and its modulation by biological and ecological factors using a Bayesian phylogenetic generalized linear mixed model across 915 bird species. Our results support Hesse's rule: species in colder climates have larger hearts (after controlling for body mass) than their relatives in warmer areas. Additionally, we found that body size, flight mode, migratory behavior, and territoriality significantly influence the relationship between heart size and environmental temperature. These findings collectively demonstrate that the evolution of heart size is not governed by a singular environmental driver but is shaped by a complex interplay of selective pressures, including thermoregulatory demands, locomotor strategies and behavioral adaptations. Future studies should aim to uncover the physiological mechanisms behind these effects and assess their generality across wider ecosystems and taxa, thereby advancing our understanding of how climate influences physiological traits and evolutionary pathways.
Dispersal is a key ecological trait that ensures connectivity, gene flow, and range dynamics, yet empirical information about how dispersal distances vary within species remains scarce. Many studies, investigating for instance connectivity conservation, use typical species-specific dispersal kernels without accounting for the fact that these kernels actually emerge from an interaction between species traits and the landscape context. Here, we aim to analyse the influence of habitat amount and fragmentation, two key elements of landscape context, on dispersal kernels. To test this, we use an individual-based modelling platform to simulate movement trajectories of four types of animal species, from insects to mammals, across artificial landscapes varying in habitat amount and fragmentation. From these simulated movements we derived dispersal kernels using five probability density functions and related dispersal distances to landscape context. Log-normal (fat-tailed) kernels consistently best described dispersal across species, but both median and long-distance dispersal varied strongly with habitat configuration. Habitat fragmentation strongly shaped emerging dispersal kernels across species as it directly influenced movement trajectories, while habitat amount had a lesser and more ambiguous effect on dispersal distances. Our results highlight that dispersal kernels for a given species depend strongly on habitat fragmentation and amount, and therefore cannot be assumed constant across landscapes, limiting the transferability of empirically derived species-level dispersal kernels to new landscape contexts. Improving predictions of dispersal under global change will require explicit consideration of intraspecific variation in dispersal driven by landscape context in both empirical and model-based studies, and further investigation of additional context-dependent drivers of dispersal variation.
Novel parasite introductions are threatening wildlife communities globally. The degree of threat depends on the ecological context, namely host community characteristics and the presence of other parasites. How these two factors interact to shape the outcomes of parasite introductions is not known. We experimentally investigated how infection following introduction of the amphibian parasite, Ranavirus ( Rv ), is influenced by host species identity, host species richness, and previous exposure to the fungal parasite, Batrachochytrium dendrobatidis ( Bd ). We varied Bd exposure history prior to introducing Rv in host communities of either larval common toads Bufo bufo , larval common frogs Rana temporaria , or both host species together. Interactive effects of host species identity and host species richness were responsible for driving Rv infection patterns, more so than Bd exposure history. Notably, the host species at highest risk of Rv infection changed between one‐species and two‐species host communities. In one‐species contexts, frog tadpoles were more likely to exhibit Rv infections than toad tadpoles. When the two species were co‐housed, Rv infection probability in toads increased to levels comparable to frogs. Prior exposure to Bd did not alter these patterns. Overall, host community context was the key predictor of Rv infection risk following its introduction into amphibian communities. These results show that host roles in pathogen maintenance may be dynamic and change depending on host community characteristics. Such changes likely have important implications for biodiversity–disease relationships that so far remain overlooked.
Animals consume foods in specific quantities and ratios to meet a multi‐dimensional nutrient target that maximizes their fitness. Attempts to reach this target in an ever‐changing nutritional landscape often influence animal foraging behavior, habitat choice, and food‐web interactions. Consequently, understanding the nutritional ecology of a species is instrumental in developing efficient management plans for its conservation. We quantified the dietary considerations of a critically endangered population of Acacia gazelles Gazella arabica acacia , and compared their diet and nutrition to that of the sympatric Gazella dorcas ,using behavioral observations coupled with nutritional and secondary metabolite quantification, and morphological measurements of trees. Acacia gazelles mainly consumed resources from two subspecies of the umbrella‐thorn acacia Vachellia tortilis that differ in morphology, nutritional composition and phenology, targeting specific trees based on their nutritional and defensive traits. Gazelles maintained a narrow nutritional target, tightly regulated their protein intake, and aimed to increase consumption of non‐structural carbohydrates. Dorcas gazelles consumed a very different diet from the Acacia gazelle, but converged to a similar intake target. By considering both dietary and nutritional data, we conclude that suitable habitats for Acacia gazelle reintroduction must include sympatric populations of the two V. tortilis subspecies, that nutritional deficiency is unlikely to play a major role in explaining the slow rate of population recovery, and that the seemingly low competition between the two gazelle species does not necessitate controlling the Dorcas gazelle population. Our results link species‐specific dietary strategies with resource selection and resulting interspecific interactions, demonstrating the importance of nutritional ecology as a major conservation tool.
