The Journal Of Animal Ecology[JOURNAL]
Sun
200 papers
Coupled effects of forest growth and climate change on small mammal abundance and body weight: Results of a 39-year field study.
Dri GF, Bogdziewicz M, Hunter M … +2 more , Witham J, Mortelliti A
J Anim Ecol · 2025 Oct · PMID 40842113 · Publisher ↗
In rapidly changing environments, the combined effects of climate change and forest stand changes-such as growth or regeneration-are altering the availability of resources, particularly in systems with pulsed resources l...
In rapidly changing environments, the combined effects of climate change and forest stand changes-such as growth or regeneration-are altering the availability of resources, particularly in systems with pulsed resources like seed-masting. These environmental shifts can have cascading impacts on animal populations, ultimately reshaping ecosystem structure and function. However, relevant studies are rare as they require long-term monitoring of both seed supply and animal populations. We investigated how temporal changes in resource availability (red oak acorns [Quercus rubra]) influence the demographics and physical traits of white-footed mice (Peromyscus leucopus) using a 39-year dataset from Maine, USA, which includes: mouse abundance and body weight, red oak tree size and acorn production, and seasonal temperatures. Our analysis of 5032 individual mice revealed a significant increase in both abundance (by 67%) and average body weight (by 15%) over four decades. We found that oaks produced more acorns as they grew, while warmer spring temperatures led to larger crops. This indicates that both forest growth and climate change have driven the increase in resource availability. The increase in acorn production was translated into higher mouse abundance and body weight. Notably, heavier mice also showed a higher probability of survival. These results demonstrate that changes in food supply, driven by the combined effects of forest growth and climate change, have significant effects on animal population dynamics. Furthermore, given the important role of white-footed mice as seed predators and dispersers, and disease vectors, these shifts have far-reaching implications for the ecosystem.
Life history induces markedly divergent insect responses to habitat loss.
Colares LF, Peres CA, Dambros CS
J Anim Ecol · 2026 Jan · PMID 40842109 · Full text
Habitat loss poses a major threat to tropical biodiversity, but its effects on distinct taxa remain unclear. Furthermore, most studies have failed to investigate the effects of habitat loss for taxa with contrasting life...
Habitat loss poses a major threat to tropical biodiversity, but its effects on distinct taxa remain unclear. Furthermore, most studies have failed to investigate the effects of habitat loss for taxa with contrasting life histories, potentially underestimating those impacts. Here, using an unprecedented sampling effort, we investigated the effects of forest amount on the diversity, composition and size structure of Amazonian terrestrial and aquatic insects. We sampled the insect fauna across Earth's largest man-made forest archipelago 36 years after impoundment (Balbina reservoir, Central Amazon, Brazil) using 236 sticky traps placed on forest islands, the open-water matrix and adjacent continuous forests. Using fivefold cross-validated computer vision models, we identified and measured 22,471 individual insects. To consider sampling bias on diversity estimation, we used individual-based rarefaction to partition diversity into components that explained community evenness and regional species pool size. We also applied coverage-based rarefaction to estimate changes in community composition, reducing potential bias. Low forest amount led to low dominance of terrestrial insects; conversely, it boosted populations of aquatic insects. We report similar effects of forest cover on regional species pool size of aquatic and terrestrial insects, highlighting the importance of large tracts of forest within the landscape to foster diverse communities. Large terrestrial insects were most likely to disperse across the inhospitable floodwater matrix compared to their smaller counterparts. Future studies should consider multi-taxa approaches to properly quantify impact estimates of land-use change on biodiversity, which can diverge widely depending on species life history traits. Generalizations and any target conservation action cannot be made without explicitly considering how forest cover can affect species depending on their life history traits.
Loss of distinct functionality during fish community disassembly.
Ji S, Li Y, Ding C … +3 more , He D, Tao J, MacIsaac HJ
J Anim Ecol · 2025 Nov · PMID 40842096 · Full text
Human-induced environmental changes increase species turnover, typically characterized by native species extirpation and non-native species (NNS) invasions, leading to multiple functional consequences owing to varying sp...
Human-induced environmental changes increase species turnover, typically characterized by native species extirpation and non-native species (NNS) invasions, leading to multiple functional consequences owing to varying species roles and whether losses from extirpation are compensated by newly established NNS. We analysed community functional roles among fish species that persisted, were extirpated or were newly established over 75 years (1940-2015) in 15 lakes in southwest China, using functional diversity indices and trait-based network analyses. While species extirpation rate increased strongly through time, earlier extirpations caused the greatest losses to novel functional diversity. Functional losses from native species extirpation were not compensated by NNS. Functional patterns of extirpations were mainly random or overdispersed, whereas invasions were almost always random species replacements. Synthesis and applications. Our findings highlight that the loss of distinctive functional diversity persists even when extirpation rates are low, due to the incomplete functional replacement of native species by NNS, which are typically functionally random relative to extirpated species. This underscores the importance of prioritizing the protection of functionally distinct species to preserve community integrity. Additionally, our use of trait-based network analysis provides a novel perspective for understanding the functional implications of species turnover, and could be a valuable tool for researchers and conservation practitioners to evaluate community assembly processes and functional structure dynamics.
Temporal niche partitioning: Mechanism of coexistence or competitive exclusion via priority effects?
Zou HX
J Anim Ecol · 2025 Oct · PMID 40820934 · Publisher ↗
Research Highlight: Ekrem R., de Vries, C., Kaiser, T., & Kokko, H. (2025). Temporal niche differentiation often leads to priority effects rather than coexistence: Lessons from a marine midge. Journal of Animal Ecology,...
Research Highlight: Ekrem R., de Vries, C., Kaiser, T., & Kokko, H. (2025). Temporal niche differentiation often leads to priority effects rather than coexistence: Lessons from a marine midge. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.70094. Temporal niche partitioning has always been hypothesized as a key mechanism in maintaining species coexistence. By utilizing resources or habitats at different times, each species will occupy distinct 'temporal niches', thereby reducing overlap in resource use and the potential for competitive exclusion. However, to what extent temporal niche partitioning can explain coexistence remains contested, as increasing theoretical and experimental evidence finds weak contributions of such temporal mechanisms to community dynamics. In a recent study, Ekrem et al. (2025) shed new light on this debate by studying the complex life history of coexisting strains of the marine midge, Clunio marinus. Using mathematical models based on empirical processes, they found that the temporal differentiation of breeding phenology between strains does not always lead to coexistence. Instead, the first strain that emerges and breeds will benefit from a positive frequency dependence, leading to priority effects that promote the exclusion of other strains. These results highlight the nuanced role of temporal niche partitioning and related mechanisms in contributing to coexistence, emphasizing the importance of system-specific knowledge in considering the consequences of temporal differentiations in resource and habitat use.
Transgenerational effects increase the vulnerability of a host-parasitoid system to rising temperatures.
Bright NL, Chen J, Terry JCD
J Anim Ecol · 2025 Oct · PMID 40796534 · Full text
Transgenerational effects, non-evolutionary processes by which environmental conditions in one generation influence the performance in subsequent generations, are hypothesised to have substantial consequences for populat...
Transgenerational effects, non-evolutionary processes by which environmental conditions in one generation influence the performance in subsequent generations, are hypothesised to have substantial consequences for population dynamics under stochastic environments. However, any direct apparent detriment or advantage these processes generate for a focal species may be counteracted by concurrent effects upon interacting species. Using an experimental Drosophila-parasitoid model system, we determined how the previous generation's thermal environment impacts the thermal performance of both hosts and parasitoids. We found substantial responses in both trophic levels, with potential evidence for both condition-transfer effects and adaptive transgenerational plasticity. We used these results to parameterise discrete-time simulation models to explore how transgenerational effects of thermal conditions and temporal autocorrelation in temperature are expected to impact the time to extinction for this host-parasitoid system under climate change. The models predicted that transgenerational effects would significantly hasten the time to extinction, largely through a reduction in estimated average performance. Under the assumptions of one of the population dynamics models trialled, we identified an additional hastening of extinction from the combined effect of both host and parasitoid transgenerational effects. Our research demonstrates how community-level consequences of transgenerational effects may impact a population's sensitivity to climate change under a fluctuating environment and highlights the need to quantify and contextualise thermal transgenerational effects in their ecological setting.
Correction to 'Salmon lice from aquaculture reduce marine survival of Atlantic salmon'.
J Anim Ecol · 2025 Sep · PMID 40765151 · Publisher ↗
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Novel contributions to marine heatwave ecology: Identifying and addressing knowledge gaps in ecological impacts.
Gómez-Gras D, Linares C, Capdevila P
J Anim Ecol · 2025 Aug · PMID 40765116 · Publisher ↗
As the climate crisis unfolds, marine heatwaves (MHWs), defined as discrete periods of anomalously high seawater temperatures, are emerging as one of the most pervasive threats to marine biodiversity worldwide. From coas...
As the climate crisis unfolds, marine heatwaves (MHWs), defined as discrete periods of anomalously high seawater temperatures, are emerging as one of the most pervasive threats to marine biodiversity worldwide. From coastal shallow waters to the deep sea, increasingly frequent and intense MHWs are reshaping ocean life at all levels of ecological organisation, undermining ecosystem resilience and compromising the provision of essential ecosystem services to human societies. This growing environmental challenge has rendered a new scientific discipline-marine heatwave ecology-which aims to advance our understanding, forecasting capacity and mitigation of MHW impacts on ecological systems. These priorities are central to marine science and conservation. Yet, despite increasing scientific attention, many critical research questions remain unresolved. In this cross-journal Special Feature, published across the Journal of Animal Ecology, Journal of Ecology and Functional Ecology, we present a collection of 13 studies that address some of the most pressing knowledge gaps in MHW ecology. These studies were conducted across diverse ocean basins and encompass a wide range of marine taxa, such as corals, macroalgae, seagrasses, molluscs, fish and plankton, among others. They span multiple levels of ecological organisation, from individual organisms to entire ecosystems, and employ a variety of methodologies and approaches. Collectively, the contributions to this special feature demonstrate how MHWs erode ecosystem resilience, reveal previously hidden biological and ecological impacts and show that vulnerability not only depends on thermal tolerance but also on environmental context. The studies also explore how MHW effects cascade up and down across levels of ecological organisation and reinforce the importance of applying ecological frameworks to better categorise and understand MHW dynamics. Finally, we have identified remaining knowledge gaps to guide future research, essential to further develop the MHW ecology field and to inform more effective conservation and management strategies. This will be especially urgent in the context of a rapidly warming ocean, where strong and recurrent MHWs are becoming the new normal.
Strong context dependence in the relative importance of climate and habitat on nation-wide macro-moth community changes.
Guilbault E, Sihvonen P, Suuronen A … +6 more , Huikkonen IM, Pöyry J, Laine AL, Roslin T, Saastamoinen M, Vanhatalo J
J Anim Ecol · 2025 Oct · PMID 40760714 · Full text
Habitat modification and climate change are major threats to biodiversity. Understanding the magnitude of their impact and their relative contributions across large spatial scales is important but challenging, given pote...
Habitat modification and climate change are major threats to biodiversity. Understanding the magnitude of their impact and their relative contributions across large spatial scales is important but challenging, given potential context dependence and biases arising from data gaps. Here, we apply a novel predictive framework to tackle these challenges in a study of community data across multiple climatic zones. We used joint species distribution modelling to analyse moth species' occurrence and abundance variation in response to the climate and habitat characteristics within a landscape of 109 sites across Finland spanning 23 years. To correct for spatiotemporal gaps in survey data, we used predictions from the fitted models to evaluate the relative importance of individual drivers on species' occurrence and abundance variation, as well as their effects on community diversity, across the entire country (i.e. beyond the sampled sites). To characterise potential context dependence, we extended model predictions with conditional variance partitioning analysis across species grouped by their functional similarity (functional context) and across sites grouped by the most dominant habitat types (environmental context). Finally, to assess the magnitude of each driver's effect alone on community-level change, we implemented separate scenario predictions for changes in climate only vs. changes in habitat only. Our results show that the dynamics of communities depended on both functional and environmental contexts. Across Finland, variation in species occurrence was mostly explained by habitat characteristics, but the relative importance of climate and habitat varied according to species functional characteristics and to the dominant habitat types within a landscape. Consequently, temporal trends in community diversity varied across space, and temporal predictions based on changes in climate only vs. changes in habitat characteristics only missed important features of the realised community dynamics. Our results underpin the importance of habitat composition as a key driver of community change-even among temperature-sensitive ectotherms. Climate and habitat contributed unequally to species occurrence and abundance, and consequently, predictions based on a single driver of environmental change misrepresented realised community dynamics. To understand and predict community change, we thus need to account for the imprints of both climate and land use.
Canopy ants are out in the cold in temperate forests.
Senior RA
J Anim Ecol · 2025 Sep · PMID 40727994 · Publisher ↗
Research Highlight: Kirchner, Michelle; Sorenson, Clyde; Youngsteadt, Elsa (2025). Too cold to handle: Climatic constraints on arboreal ants in temperate forests. Journal of Animal Ecology. Ants are among the most abunda...
Research Highlight: Kirchner, Michelle; Sorenson, Clyde; Youngsteadt, Elsa (2025). Too cold to handle: Climatic constraints on arboreal ants in temperate forests. Journal of Animal Ecology. Ants are among the most abundant animals on the planet and they have a huge impact of ecosystems worldwide. Being small-bodied ectotherms, their growth, survival and reproduction is closely tied to the temperatures they experience (the microclimate), and hence the thermal physiology of different ant species determines their global and regional distribution and is subject to change under climate warming. Forest habitats present a significant additional climate gradient from ground to canopy, and its implications for tropical ant species have been reasonably well explored. Yet these findings cannot easily be easily applied to temperate forests, where seasonal variation in temperature and vegetation could mean very different things for ant communities. Kirchner, Sorenson, & Youngsteadt (2025) address this research gap by measuring the thermal tolerance of ants collected from the ground and canopy, across seasons, and alongside measurements of air and nest temperatures. As elsewhere, ants that experience a broader range of temperatures-in this case, canopy ants-have a broader thermal tolerance than those experiencing more stable temperatures-the ground-dwelling ants. Ants from both strata adapted their cold tolerance to cope with winter cold, while heat tolerance did not change, in line with previous evidence that heat tolerance is a less labile trait. Perplexingly, however, canopy ants were less tolerant of winter cold despite being far more exposed to extreme cold. Thus, this paper provides an intriguing insight into how ecophysiological rules play out for ants across the vertical gradient of temperate forests, suggesting that canopy ants here are more limited by tolerance of winter cold. This could suggest that the diversity of temperate forest canopies may increase as winters become less extreme, which could have important implications for temperate forest ecosystems.
Does a lack of juveniles indicate a threat? Understanding body size distributions in a group of long-lived vertebrates.
McKnight DT, Bower DS, Ariel E … +27 more , Beatty S, Clulow S, Connell M, Deppe AR, Doody S, Freeman A, Georges A, Hannabass SL, Hollender EC, Howell H, Krochmal A, Ligon DB, Munscher E, Nordberg EJ, Roth TC, Santoro A, Schaffer J, Simms A, Spencer RJ, Stone P, Voves KC, Walde AD, Wassens S, Welsh MA, Whiterod NS, Wirth W, Van Dyke JU
J Anim Ecol · 2025 Oct · PMID 40727957 · Full text
Turtles are declining globally, and absences of juveniles during surveys are often interpreted as evidence of threats to early life stages. In Australia, for example, it is widely argued that a low number of juveniles is...
Turtles are declining globally, and absences of juveniles during surveys are often interpreted as evidence of threats to early life stages. In Australia, for example, it is widely argued that a low number of juveniles is likely due to nest predation by introduced red foxes (Vulpes vulpes). However, small sample sizes within populations, low detectability of juveniles and turtles' long lifespans often confound the conclusion that a paucity of juveniles indicates a declining population. Because turtles have long reproductive lifespans, we might intuitively expect most turtle populations to be heavily weighted towards large individuals, but a 'typical' or 'healthy' size distribution for turtle populations has not been well established. Therefore, we collated data on 41,021 freshwater turtles from 38 species and 428 populations located in parts of Australia both with and without introduced foxes, as well as populations in the United States of America, which naturally have raccoons (Procyon lotor), foxes and other nest predators. We examined population-level body size distributions to establish a baseline for 'typical' turtle populations and test whether populations that are exposed to introduced foxes have proportionately fewer juveniles compared to both AU populations that lack introduced foxes and USA populations that are naturally exposed to nest predators. We found that most turtle populations in AU and the United States were heavily skewed towards adults and had few juveniles, regardless of the presence of foxes or other nest predators. There were, however, clear differences among population survey methods: those that target shallow areas (e.g. crawfish traps) tended to capture proportionately more juveniles, and small sample sizes (∼<50) often produced inaccurate representations of size distributions. Additionally, we used a simulation to demonstrate that, given common turtle life history parameters, even stable populations should generally have low proportions of juveniles. Based on our results, we encourage caution when interpreting turtle size distributions. A small number of juveniles does not inherently suggest that a population is declining due to high egg and/or juvenile mortality, and researchers should pay careful attention to the biases in their methods and strive to capture a minimum of 50-100 turtles before drawing inferences.
Guild diversity impacts demographic outcomes of novel species interactions following range shifts.
O'Connor M, Lancaster LT
J Anim Ecol · 2025 Oct · PMID 40709484 · Full text
Novel competitive interactions between native and range shifting species can precipitate local extinction of native species. However, increased biological complexity within recipient communities may prevent native specie...
Novel competitive interactions between native and range shifting species can precipitate local extinction of native species. However, increased biological complexity within recipient communities may prevent native species loss by decreasing the strength of novel competition experienced by any one species. This phenomenon, termed 'biotic resistance', is commonly applied in invasion ecology, but has received little attention in the context of climate induced range shifts. Here we investigate the effects of biotic resistance in competition between resident native and range-shifting damselflies in a region of Scotland newly colonised by the range-shifter, using competitive mesocosm treatments across multiple life stages and experimental temperatures. Our focal native species (Lestes sponsa) was unaffected by increasing competitive complexity as larvae, showing no fitness benefits in multispecies treatments compared to intraspecific or even interspecific scenarios in the presence of the range shifter. However, multispecies competition with both native and range-shifting species improved adult survival of our focal native species at higher temperatures, compared to interspecific competition with just the range shifter. For our focal range-shifting species (Ischnura elegans), larval growth rate was significantly reduced in multispecies treatments compared to intraspecific or two-species interspecific scenarios, yet adult range shifter survival showed no decrease in multispecies treatments. Furthermore, range shifter larvae displayed improved survival and growth in colder temperatures, compared to a lack of any temperature effects on adult survival. These results suggest that biotic resistance may alleviate the competitive impacts of range shifters on native communities by providing a life stage-dependent benefit to native species while simultaneously decreasing the fitness of range shifters. However, shifting temperatures can cause this interaction to swap between competition and facilitation, creating an environmentally dependent scenario that may benefit both range shifters and resident species, promoting the maintenance of diversity in high latitude communities.
Tropical fishes can benefit more from novel than familiar species interactions at their cold-range edges.
Mitchell A, Hayes C, Coni EOC … +2 more , Booth DJ, Nagelkerken I
J Anim Ecol · 2025 Oct · PMID 40702600 · Full text
Animals extending their biogeographic ranges poleward under global warming often interact with local species for limited resources such as food and shelter. Whether such novel species interactions facilitate or inhibit r...
Animals extending their biogeographic ranges poleward under global warming often interact with local species for limited resources such as food and shelter. Whether such novel species interactions facilitate or inhibit range extensions remains largely unknown. We evaluated how range-extending tropical and co-shoaling temperate fishes modify their behaviours (aggression, foraging and anti-predator) along a 2000-km latitudinal gradient encapsulating tropical, subtropical and temperate reefs in a global ocean warming hotspot. All five tropical fish species showed increased anti-predator behaviours and decreased bite rate at their novel temperate range compared to their native tropical and subtropical ranges. However, when shoaling with temperate fishes, three of five tropical fish species had higher bite rates and all five tropical fish species spent less time sheltering compared to tropical-only shoals, irrespective of biogeographic region. In their subtropical ranges, tropical fish were more aggressive towards co-shoaling temperate fish compared to their poleward novel cold ranges. This increased tropical fish aggression resulted in increased fleeing responses by the two temperate fishes at their subtropical warm trailing edges compared to their warm- and cold-temperate core ranges. Our findings suggest that tropical fish species trade-off foraging efficiency for anti-predator behaviour in their novel warm- and cold-temperate ranges, independent of shoaling interactions. However, shoaling with temperate species can increase the foraging efficiency of tropical fishes, which may be a mechanism (phenotypic plasticity) that enhances their performance at their leading temperate range edges. Since novel species interactions enhanced the behavioural performance of some tropical fishes, we conclude that behavioural interactions between range-extending and local species can facilitate successful range extensions of some species into novel environments.
Temporal niche differentiation often leads to priority effects rather than coexistence: Lessons from a marine midge.
Ekrem RK, de Vries C, Kaiser TS … +1 more , Kokko H
J Anim Ecol · 2025 Oct · PMID 40685516 · Full text
While niche differences aid coexistence, the role of temporal niches is complex. A recent study (Stump & Vasseur, 2023) casts doubt on the idea that species coexist easily if they partition abiotic niches that vary in ti...
While niche differences aid coexistence, the role of temporal niches is complex. A recent study (Stump & Vasseur, 2023) casts doubt on the idea that species coexist easily if they partition abiotic niches that vary in time. The storage effect, which aids coexistence, requires that species differ in what is a 'good year', and that the benefits that the currently common species can draw from its own good year become limited due to intraspecific competition. The recent re-evaluation of temporal niches considered Allee effects only fleetingly. We complement their work by providing a case study of the marine midge Clunio marinus, where coexistence appears to occur in nature, is associated with a strong difference in timing traits, and also features Allee effects because rare timing phenotypes emerge with limited mating opportunities. The larvae develop in the sea, and adults emerge and mate during the lowest low tides. These tides coincide with either the full or the new moon, and genetically determined strains use either one of them, or both, for emergence. A 'good year' in this system translates into a particular low tide. Allee effects create strain-specific good tides if the risk of hybridization is greater for the currently rare strain, which mates more often with another strain, than the currently common strain. We are able to investigate this effect by varying the effects of hybridization in our model of Clunio biology. Temporal niches, mate-finding Allee effects, hybridization possibilities and a potential growth-survival tradeoff do not easily combine to yield stable coexistence. Most factors instead promote positive frequency dependence, leading to priority effects. Ontogenetic niche shifts among larvae deviate from this result: if suitably timed, they are able to concentrate competition in a coexistence-promoting manner. Our study thus complements and strengthens Stump and Vasseur's conclusion that a finding of temporal niche differentiation should not be straightforwardly assumed to be an explanation for the coexistence of two or more morphs or species. We encourage linking temporal niche studies with those of priority effects, as well as the study of other coexistence mechanisms that may operate within systems that feature temporal niches.
Host avoidance and resistance vary independently and are specific to parasite genotype.
Amoroso CR, Lockwood-Shabat A, Kamali A … +1 more , Gibson AK
J Anim Ecol · 2025 Oct · PMID 40679145 · Full text
Hosts can reduce the negative fitness effects of parasite infection by avoiding contact with parasites or by resisting infection after contact. Because of their shared outcome, avoidance and resistance have been hypothes...
Hosts can reduce the negative fitness effects of parasite infection by avoiding contact with parasites or by resisting infection after contact. Because of their shared outcome, avoidance and resistance have been hypothesized to trade off with one another. Assuming these defences carry fitness costs, hosts are expected to have high levels of one defence or the other, but not both. Alternatively, avoidance and resistance may covary positively, if, for example, they complement one another or are genetically or mechanistically linked. Testing these hypotheses requires measuring avoidance and resistance independently, which is challenging because they are functionally linked. In this study, we separated avoidance and resistance of the host Caenorhabditis elegans against the bacterial parasite Serratia marcescens and tested for a correlation between them. We phenotyped a panel of 12 genetically divergent hosts using two distinct bacterial strains and multiple experimental contexts. We found no evidence of a correlation between avoidance and resistance. This result suggests that avoidance and resistance can covary independently. Moreover, we found strong strain specificity not only for resistance, but also for a measure of avoidance, motivating further research to examine the coevolutionary dynamics of avoidance.
Defaunation erodes the diversity of rodent personality traits in fragmented forests.
Zeng D, Matthews TJ, Wang R … +4 more , Zhao Y, Yan C, Ding P, Si X
J Anim Ecol · 2025 Oct · PMID 40673613 · Publisher ↗
Habitat fragmentation is a primary driver of biodiversity loss globally. One impact of habitat fragmentation is the resultant decline and loss of large and medium mammal populations (also known as defaunation). While the...
Habitat fragmentation is a primary driver of biodiversity loss globally. One impact of habitat fragmentation is the resultant decline and loss of large and medium mammal populations (also known as defaunation). While the effects of habitat fragmentation and associated defaunation on species diversity are well documented, their impacts on intraspecific diversity are less studied. One understudied source of intraspecific diversity is the animal personality traits within populations. As individuals with contrasting personality traits may disproportionately contribute to ecosystem functions, losing diversity of personality traits could thus impair ecosystem functions, even if some individuals of the species still persist. However, it is still unclear how the diversity of animal personality traits changes in fragmented habitats with severe defaunation. Here, we conducted mammal surveys and comprehensive behavioural assessments of Niviventer confucianus (Chinese white-bellied rat)-the most abundant rodent-on 11 forested islands in Thousand Island Lake, China, a fragmented reservoir island system formed by dam construction. We used Bayesian structural equation modelling and a functional diversity framework considering intraspecific variation to disentangle the direct and indirect effects of habitat fragmentation and defaunation on the functional diversity of N. confucianus personality traits. We found that defaunation directly decreased the functional divergence of N. confucianus personality traits. Decreasing island area indirectly reduced the functional divergence of N. confucianus personality traits through intensifying defaunation. We also found that island area directly increased rodent abundance but simultaneously exerted an indirect negative effect via defaunation. However, we did not find an effect of rodent abundance on the functional divergence, nor any effects of habitat fragmentation and defaunation on the functional richness or functional evenness of N. confucianus personality traits. These results indicate that defaunation may play a key role in mediating the negative effects of habitat fragmentation on animal behavioural diversity. The defaunation-resultant declines of intraspecific behavioural diversity highlight the importance of measuring intraspecific diversity to better understand the ecological consequences of human-driven environmental changes on biodiversity.
Thermal performance curves, activity and survival in a free-ranging ectotherm.
Wild KH, Roe JH, Curran J … +4 more , Pearson PR, Schwanz L, Georges A, Sarre SD
J Anim Ecol · 2025 Sep · PMID 40668123 · Full text
Temperature profoundly influences the distribution and diversity of ectotherms, yet in natural settings, interactions between environmental temperatures, behaviour, physiological function and the influence of these facto...
Temperature profoundly influences the distribution and diversity of ectotherms, yet in natural settings, interactions between environmental temperatures, behaviour, physiological function and the influence of these factors on individual survival remain poorly understood. In particular, it is unclear as to how trade-offs between these factors are optimised in wild, free-ranging species. We combined temperature-sensitive radio transmitters and accelerometers to measure in situ body temperatures and field-based thermal locomotor performance, estimating thermal optimum and maximum performance. This allowed us to quantify the effectiveness of thermoregulation in the wild and determine whether seasonal trade-offs in thermoregulatory behaviour shape thermal performance and influence survival in the Australian central bearded dragon (Pogona vitticeps). Lizards adjusted their behaviour to maintain optimal body temperatures, achieving greater thermoregulatory precision in spring and summer when environmental costs of thermoregulation were low, but reducing that precision in winter when costs were higher. Activity time and maximum locomotor performance were higher during seasons when thermoregulatory precision was high. Maximum locomotor performance in the field was a strong predictor of survival, regardless of sex, even though survival probabilities were higher in males than females. Higher locomotor performance was associated with increased mortality risk, but survival was not influenced by activity levels or thermoregulatory indices. These findings highlight the complex trade-offs that ectotherms must navigate to balance behavioural thermoregulation and survival. Our data demonstrate the important influence of seasonal and sex-specific variation on behaviour and fitness-related outcomes. Interpreting field-derived thermal performance curves alongside laboratory measures is crucial for distinguishing 'true' physiological capacity from the integrated ecological contexts that shape performance and fitness in nature. Such insights are vital for predicting how ectotherms may respond to future climate warming.
Long-term population dynamics of western tent caterpillars: History, trends and causes of cycles.
Myers JH, Cory JS
J Anim Ecol · 2025 Oct · PMID 40660707 · Full text
This is a story of unique long-term studies of the population ecology of a gregarious, cyclic forest insect, the western tent caterpillar (WTC), Malacosoma californicum pluviale. Early work by W.G. Wellington proposed th...
This is a story of unique long-term studies of the population ecology of a gregarious, cyclic forest insect, the western tent caterpillar (WTC), Malacosoma californicum pluviale. Early work by W.G. Wellington proposed that variation in the 'quality' and activity of larvae and moths influenced their population ecology. Our subsequent studies monitored six WTC populations over 29-50 years in south-western BC to determine the consistent characteristics of cyclic population dynamics. The six studied populations fluctuated more or less in synchrony with an eight to 11-year periodicity. Fecundity and tent size (an indication of early larval survival) increased with population increase and declined several years before the population peak. Fecundity and tent size were positively related to the population growth rate and declined before the population peak. Mortality from a baculovirus was high at peak densities, and the rate of population growth was negatively related to infection levels. Resistance to the virus varied among families and was higher following the epizootic at peak host density. Factors that might influence changes in fecundity were explored. Viral resistance was not related to moth fecundity, but sublethal effects as a result of surviving virus exposure could reduce fecundity. Declines in fecundity and tent size prior to the peak density could be a result of reduced foliage availability and quality from induced effects of larval feeding. Introduction and cropping experiments were unsuccessful at creating out-of-phase populations, and introduced insects appeared to carry the 'quality' of the source populations and declined synchronously with them. Warming temperatures influence the phenology of egg hatch and leaf development, but field experiments show that WTC larvae are resilient to this variation. No signal of an influence of a warming climate was apparent in long-term data. Longterm field observations indicate that changes in fecundity and viral infection can drive population cycles and inform the theory of cyclic dynamics. The early focus on variation among individuals was a prelude to the eco-evo thinking that has become accepted today but should include both genetic and phenotypic change as being relevant.
Subtle stressors-Strong responses. Consistent negative effects of avian blood parasites on phenotypic and demographic traits across songbirds.
Grabow M, Mang S, Blaum N … +3 more , Tiedemann R, Radchuk V, Kramer-Schadt S
J Anim Ecol · 2025 Oct · PMID 40650477 · Full text
Stressors that subtly yet persistently deplete energetic resources-such as heat, pollutants or parasites-are well studied in laboratory and clinical settings, where their physiological effects are often well understood,...
Stressors that subtly yet persistently deplete energetic resources-such as heat, pollutants or parasites-are well studied in laboratory and clinical settings, where their physiological effects are often well understood, yet their influence on phenotypic and demographic traits in free-living populations remains critically understudied. A prominent example is pathogens and parasites that cause sublethal infections, often considered as relatively benign, particularly in species adapted to their presence. However, parasite-induced effects on phenotypic and demographic traits are often inconsistent, leaving researchers uncertain about their impact and whether they have meaningful fitness consequences. Here, we present a meta-analysis evaluating the effects of avian blood parasites (Plasmodium, Haemoproteus and Leucocytozoon), a widespread and cosmopolitan stressor, on songbird species. Through a systematic review of 2473 publications, we identified 35 studies spanning 51 species and extracted 172 relevant effect sizes assessing host condition, phenology, reproduction and survival. Our findings reveal consistent negative impacts: reductions in body condition, reproductive success and survival, along with delays in phenological events such as breeding. Furthermore, our findings revealed a critical research gap: despite the widespread study of avian blood parasites, only a limited number provide suitable effect sizes for assessing parasite impacts on demographic traits-let alone behavioural traits. This scarcity of data highlights the urgent need to understand pathogen-induced effects on animal behaviour and demography, especially in the face of accelerating global change. We advocate for an integrative approach, combining behavioural, phenotypic, and demographic traits, to uncover the cascading consequences of parasitic infections on wild populations.
Environmental and human factors shape the trophic ecology of a widespread marine predator.
Fernández-Corredor E, Fuster-Alonso A, Ramírez F … +5 more , Giménez J, García-Barcelona S, Macías D, Coll M, Navarro J
J Anim Ecol · 2025 Sep · PMID 40635146 · Full text
Integrative approaches that investigate trophic ecology drivers provide knowledge to explore and predict changes in food-web dynamics under contrasting scenarios of global change. However, there are few studies that anal...
Integrative approaches that investigate trophic ecology drivers provide knowledge to explore and predict changes in food-web dynamics under contrasting scenarios of global change. However, there are few studies that analyse the relationship between environmental factors and trophic interactions and that additionally consider other human stressors such as fisheries. Here, we use Bayesian Stable isotope mixing models to study the trophic ecology of a widespread pelagic predatory fish, the swordfish (Xiphias gladius), in the western Mediterranean Sea and the adjacent Atlantic waters. We explore the relationships between dietary estimates and biological, environmental and anthropogenic drivers using generalized additive models (GAMs). GAMs are used to develop spatial predictions of present prey consumption and, as a prospective exercise, to project changes in prey consumption under different future climate change scenarios. Overall, we found that swordfish diet varied as a response to changing environmental conditions, particularly to varying sea surface temperature (SST), mixed layer depth (MLD) and chlorophyll-a concentration (Chl); and to fishing pressure. Fish consumption was related to SST and MLD. Squid consumption was related to SST, with the greatest contributions observed in swordfish of intermediate lengths. Squid had a higher contribution to swordfish diet around the Canary Islands and the western Mediterranean Sea, while gelatinous organisms were more consumed around the Gulf of Cádiz. The consumption of gelatinous organisms was higher in smaller swordfish and in areas with lower productivity. Our prospective exercise suggested different diet alterations under contrasting future global change scenarios. For the first time, we provide quantitative evidence of how large-scale, spatial-temporal patterns in fishing pressure and environmental conditions can shape the diet of swordfish. Our study presents useful results to assess the diet of this predator and highlight how incorporating trophic interactions into projections can improve our understanding of future distributions.
Selective logging weakly influences species co-occurrence in a community of tropical understorey birds.
Costantini D, Messina S, Weiss J … +5 more , Tomassi S, Cosset CCP, Benedick S, Bellisario B, Edwards DP
J Anim Ecol · 2025 Sep · PMID 40629526 · Full text
Selective logging is a major driver of tropical land-use change, causing reductions in forest specialist species with concurrent increases in edge-tolerant species. A key question is understanding how selective logging i...
Selective logging is a major driver of tropical land-use change, causing reductions in forest specialist species with concurrent increases in edge-tolerant species. A key question is understanding how selective logging impacts co-occurrence and assembly mechanisms in vertebrate communities as forests recover post-logging. Using a 10-year, repeat-sample study of understorey bird species in Borneo, we compare the structure of species co-occurrences over time between old-growth unlogged and logged forests, investigating the roles of functional traits and local abundance in driving co-occurrence patterns. Co-occurrence patterns were resilient to selective logging over time, although patterns were not consistent across all species in both forest types. Species with more specialised diets showed a significant tendency towards low fidelity, while species that engage in aerial foraging, soaring and gliding exhibited a significant tendency to have low values of fidelity in both types of forest. Changes in co-occurrence patterns were also significantly influenced by changes in local abundance. Our results indicate that niche segregation and environmental filtering operate to shape the assemblage of the avian community in both forest types, but co-occurrence was resilient to selective logging over time. Our results also underscore the role of some species in regulating avian assemblages and the long-term conservation value of logged tropical forests.
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