Journal of Animal Ecology最新文献

Energetic acquisition and growth are key traits that affect demography and life-history strategies. Many animals that live in seasonal environments in which food availability fluctuates store energy endogenously as fat in anticipation of food shortage. Fat-storing mammalian hibernators are an extreme example of this strategy wherein the optimal resolution of resource allocation trade-offs is essential to survival. Hence, these species provide an opportunity to test potential causes and consequences of seasonal body mass dynamics. We used a 12-year dataset of 8753 body mass records from 3351 individually marked northern Idaho ground squirrels (Urocitellus brunneus)-a federally threatened hibernator-to meet three objectives: (1) document seasonal body mass changes by sex, age and reproductive status, (2) test ecological hypotheses to explain spatiotemporal variation in body mass and (3) document fitness consequences of pre-hibernation body condition via condition-dependent overwinter survival. Squirrels varied substantially in seasonal body mass dynamics. The magnitude (36-155%) and onset (late May to early July) of rapid active-season mass gain varied among demographic groups. Reproductive females acquired the necessary fat stores to survive hibernation later in the active season than did males and non-reproductive females. Moreover, squirrels with better pre-hibernation body condition were more likely to survive to the subsequent year, potentially because they allocated excess energetic reserves to prolonging hibernation via early immergence and thereby reduced predation risk. These results suggest a direct trade-off between current and future reproduction mediated by resource acquisition and allocation, as predicted by life-history theory. Colder active-season temperatures and lower conspecific densities negatively influenced squirrel body condition, possibly via reductions in foraging activity associated with those conditions. These ecological effects on body condition constrain resource allocation and demographic outcomes. As such, our results can help guide research and conservation strategies to benefit hibernating animals.

While biotic factors such as traits, abundance or community context have long been recognized as the main determinants of species interactions, abiotic conditions such as temperature can rewire these interactions even when species composition and abundance remain constant. Interaction establishment in plant–pollinator systems is particularly sensitive to these conditions, as pollinator metabolism, cognition and behaviour and floral reward production all respond strongly to thermal variation. Yet empirical evidence for community-wide consequences of such temperature-driven shifts in interactions remains limited. Arrowsmith et al. (2025) demonstrate that changes in temperature, independently of species turnover, can trigger pollinators' flexibility in floral resource use, reshaping which flowers they visit in natural diverse communities. These findings suggest that, alongside trait matching, abundance, phylogeny or spatiotemporal overlap, temperature plays a substantial and previously underappreciated role in shaping plant−pollinator interaction patterns. These thermal effects have particularly important implications at a broader scale as climate change accelerates, as temperature-driven interaction rewiring can cascade through interaction networks, influencing their emerging properties and functional outcomes. This study therefore underscores the need to incorporate the abiotic context into predictive models of these networks for anticipating how climate change may destabilize—or stabilize—ecological systems.

Research Highlight: Marco Fioratti Junod, Irene Cordero, Nadia Chinn, Jennifer Firn, Julia Holmes, Marcus Klein, Gabrielle Lebbink, Uffe N. Nielsen, Martin Schütz, Stephan Zimmermann, Anita C. Risch. (2025). Herbivory mediates the response of below-ground food webs to invasive grasses. Journal of Animal Ecology. https://doi.org/10.1111/1365-2656.70113. A recent paper by Junod et al. (2025) tested whether herbivores could mitigate the effects of invasive African lovegrass on soil biodiversity in Australian grasslands. They found that herbivores, including livestock, native mammals and invertebrates, acted to reverse four of the 13 negative effects that African lovegrass had on soil biodiversity and function. Their work demonstrated two mechanisms through which herbivores may have acted-reducing plant litter and increasing soil temperature. The paper also highlights the difficulty of predicting the response of soil biodiversity to change because of unclear interdependencies among organisms. General techniques such as food web models, isotopic tracers and more detailed study of the lives of soil organisms will help us bridge this knowledge gap.