Ecology最新文献

Ectotherms with lower maintenance costs and broader environmental tolerances are generally more resilient in human-altered landscapes and under current climate change, enhancing their chances of survival and colonization. In this study, we explored how habitat use and foraging strategy are associated with the resting metabolic rate (RMR) of spiders from habitats with significant temperature variability due to anthropogenic disturbance: native forests and young pine plantations, both in the Southern Atlantic Forest. Using open-flow respirometry at 25°C, we measured CO₂ production in immobile spiders to calculate their RMR. Key findings include: (1) all spiders showed 22%–57% lower RMR than predicted by standard metabolic equations; (2) continuous gas exchange patterns, typical of mesic-adapted species, were observed in all cases; (3) the metabolic rate scaling exponent was 0.65; (4) there were no significant RMR differences between habitats, but a negative correlation between RMR and microhabitat thermal amplitude was noted; and (5) active foragers had higher RMRs than passive foragers. These findings enhance our understanding of spider biology, physiology, and ecology, particularly in their responses to anthropogenic stressors.

Galls play a significant role in the plant–insect interactions in various ecosystems worldwide. Consequently, research on gall-inducing insects and their host plants has garnered considerable attention in recent years, with a wealth of uncompiled data. This dataset, comprising 2,059 records of 868 native species, 361 genera, and 106 families of host plants, provides valuable information regarding the Atlantic Forest biome, one of the world's most important rainforests. The five most common botanical families represented in the dataset are Myrtaceae, Asteraceae, Fabaceae, Melastomataceae, and Rubiaceae, accounting for 40.41% of all records and 40.21% of the total number of species. In addition, exotic host plant species from families such as Anacardiaceae, Asteraceae, Fabaceae, Myrtaceae, and Verbenaceae are presented. The dataset also includes 204 species of gall-inducing insects, with a large predominance of Diptera (189 species), followed by seven species of Hemiptera, four species of Lepidoptera, and two species each of Coleoptera and Thysanoptera. This study is the first to compile inventories of plant-galling insect communities and information on the diversity and distribution of insect galls and their host plants in the Atlantic Forest. The dataset highlights areas for further research on patterns of diversity and distribution and offers a foundation for developing and testing new ecological hypotheses. Researchers are encouraged to cite this data paper when utilizing the information in their publications and to inform us of the application of the data. No copyright restrictions were applied to the dataset.

Predator use of resource subsidies can strengthen top-down effects on prey when predators respond numerically to subsidies. Although allochthonous subsidies are generally transported along natural gradients, consumers can cross ecosystem boundaries to acquire subsidies, thereby linking disparate ecosystems. In coastal Arctic ecosystems, terrestrial predators like Arctic foxes (Vulpes lagopus) cross into the marine environment (sea ice) during winter to access marine resources. Arctic foxes kill seal pups and scavenge seal carrion (often remains from polar bear Ursus maritimus kills), especially when rodent abundance is low. Terrestrial predator use of marine subsidies may strengthen the top-down control of tundra food webs, but this hypothesis remained untested. We evaluated tundra food web dynamics at the terrestrial–marine interface from an ecosystem-level perspective by assessing: (1) how winter environmental conditions affect rodent abundance and marine subsidy availability, (2) the response of the Arctic fox population to this seasonal food variability, and (3) the subsequent effects of Arctic foxes on Canada goose (Branta canadensis interior) reproduction. Arctic foxes responded numerically to rodent abundance, which was positively related to snow persistence. Arctic fox abundance was positively related to polar bear body condition metrics, which were used as a proxy for marine subsidy availability. Canada goose reproductive success, in turn, was negatively related to Arctic fox abundance. Long-term trends in goose reproduction and snow persistence also indicate an ongoing phenological mismatch between nesting initiation and spring onset. Our results reveal near-term apparent competition between rodents and geese through a shared predator, Arctic foxes, contrasting with prior studies evaluating rodent–goose–predator relationships. Moreover, we establish a link between tundra and sea ice food webs by demonstrating how seal availability can affect goose reproduction indirectly by increasing Arctic fox predation on goose nests via a population response of foxes to marine resources. These marine resources are often provisioned by polar bears, and with both Arctic foxes and polar bears undergoing long-term regional declines evidently driven by climate-related changes in prey abundance and availability, we contextualize our study within ongoing climate change and highlight the vulnerability of this likely widespread terrestrial–marine linkage in a warming Arctic.

Viruses have the potential to impact host populations, but our picture of host–virus relationships is largely colored by virulent pathogens that lead to easily detectable epizootic events. Modern molecular methods have demonstrated that viruses are ubiquitous in animal populations, and the influence of these “cryptic” viruses is largely unexplored. Insects provide an ideal system to examine population-level impacts of novel, “cryptic” viruses—short generation times allow for meaningful population-level field studies over a relatively short timeframe, and their abundance and small size facilitate experimental manipulation across each life stage. Many insect species are capable of high population growth rates, potentially buffering them from pathogen-driven declines in the face of high pathogen prevalence. We explored the impacts of a recently detected non-occluded densovirus (Junonia coenia DV, JcDV) on the demography of a nymphalid butterfly, Euphydryas phaeton (Baltimore checkerspot). E. phaeton populations are known to have the capacity for rapid growth and to exhibit large, often unexplained population fluctuations. We used a field mesocosm experiment to measure the vital rates of E. phaeton under a range of levels of viral exposure over 2 years (2021 and 2022) and used these vital rates to parameterize a demographic model of population growth in each year. We found that JcDV reduced E. phaeton post-diapause larval survival, skewed sex ratios toward a male bias, and reduced fecundity in surviving females. JcDV reduced estimated population growth rates in both years, but only led to population decline in 2022. This increased impact was associated with a substantial regional drought, suggesting that the potential for this non-occluded virus to cause population decline is influenced by climatic factors. The findings of our controlled study parallel trends observed in a wild population of E. phaeton, supporting the hypothesis that JcDV can drive population decline. This study demonstrates that cryptic viruses likely influence butterfly population dynamics, especially when their effects are compounded with additional environmental stressors.

Reordering of abundances among species is a common response in communities whether affected by anthropogenic drivers or natural disturbance. However, understanding how competitive relationships drive community dynamics under global environmental change remains limited, primarily due to uncertainties related to changes in species interactions and the scarcity of long-term observations. By combining long-term data and time series analysis tools, we quantified the compositional dynamics and causal interactions among functional groups of an arid grassland community under chronic nutrient enrichment for 15 years following wildfire. We hypothesized that chronic nutrient addition would promote species reordering among dominant grasses and subordinate annual forbs after wildfire, thereby increasing biomass and compositional variation over the long term. Contrary to expectations, while the abundance of the dominant grass Bouteloua eriopoda (black grama) declined immediately after the wildfire, the increase in annual forbs under N addition did not occur until a decade later. Convergent cross-mapping revealed that annuals were causally influenced by black grama abundance and maintained relatively lower abundance in control plots. However, with N addition, this causal interaction from black grama to annuals disappeared. Accordingly, temporal variability of biomass and community composition increased as the abundance of annuals rose. Combined with evidence of precipitation response, these results imply that the competitive advantage of perennial plants over annual forbs could serve as a stabilizing mechanism for community variability by limiting the response of annuals to precipitation fluctuations. However, this stabilizing process is disrupted by the cumulative effects of chronic nitrogen addition. This long-term experiment provides new insights into the destabilizing effects of community reordering, without changes in species richness, in response to anthropogenic nutrient loading.

Biological communities are facing profound upheaval induced by global environmental change. While changes in community composition over time are now well documented, much less is known about whether concomitant shifts in trophic structure also manifest. Here, we leveraged a 10-year dataset of freshwater fish communities and stable isotope compositions in nine lakes to test whether compositional changes (i.e., changes in community structure) and local environmental factors drove trophic trajectories over time. We found marked changes in the trophic structure of fish communities across all lakes, with a general tendency toward narrower trophic niches dominated by trophically redundant species. The variations in trophic trajectories among lakes were primarily linked to differences in the temporal pace and directionality of change. Specifically, lakes exhibiting greater compositional changes displayed more irregularity in their trajectory, and communities dominated by non-native species displayed elevated trophic stability over time. Our findings reveal species turnover as the dominant factor shaping trophic dynamics, through the addition or removal of predatory species and trophic turnover. The trophic stability observed in communities that were already invaded at the start of the study could be driven by their reduced susceptibility to compositional change caused by subsequent invasions. These findings highlight the existence of strong changes in trophic niches and unveil the intricate interplay between compositional changes and biological invasions in governing the trophic trajectories of communities and food web architecture, with subsequent implications for ecosystem functioning.

As the oceans change, the abundance of parasites and the risk of infection to marine mammals may also be changing. Nematodes in the family Anisakidae can harm marine mammals, and recent studies have revealed a global increase in these parasites, but the cause is unknown. We sought to determine how anisakid risk in Puget Sound had changed over 98 years by conducting a parasitological analysis of museum specimens of the prey species of marine mammals. We dissected Pacific Herring, Walleye Pollock, Surf Smelt, Pacific Hake, and Copper Rockfish collected between 1920 and 2018. We found that the larval anisakid Contracaecum spp. was the most abundant marine mammal parasite in these prey fish. We used a state-space model to assess the relationship between Contracaecum spp. abundance and time, with harbor seal abundance and sea surface temperature as potential correlates. We detected an overall decline in Contracaecum spp. abundance with a recent uptick starting in 1989, which was correlated with increasing harbor seal abundance. While these data reveal a regional trend, increases in marine mammal parasites in response to marine mammal protection have occurred elsewhere and suggest that the phenomenon might be more widespread than is currently appreciated. Marine mammals in Puget Sound are probably less burdened by anisakids than they were historically, but the recent recovery of anisakids could impact the health of these hosts, which today face very different stressors than they did in the past.