Ecology最新文献

Dispersal is becoming increasingly critical to understand as climate change forces species to shift their ranges to track changing environments. Although we know that warmer temperatures can prompt species to shift their ranges, we have little understanding of how temperature affects the speed at which they can do so by altering the rate of range expansion. Warmer temperatures could accelerate the rate of range expansion by increasing random, density-independent movement and/or by increasing population growth rates and driving density-dependent movement. To test the effect of temperature on the rate of range expansion, we grew populations of the flour beetle Tribolium castaneum in linear connected landscapes at 27.5, 30, or 32.5°C and tracked their expansion for 18 weeks. We then conducted separate assays to isolate the effect of temperature on density-independent dispersal probability and population growth rates. We found that beetles at 32.5°C exhibited the fastest range expansion, and that higher temperatures increased both dispersal probability and population growth rates, suggesting that both mechanisms likely contributed to faster range expansions under warming. Our findings highlight the importance of assessing the effects of temperature on range expansion dynamics in order to fully understand how, and how quickly, ranges will shift under climate change.

Under the current global biodiversity crisis, there is a need for automated and noninvasive monitoring techniques that can gather large amounts of data cost-effectively at various ecological scales, from local to large spatial scales. These data can then be analyzed to inform stakeholders and decision-makers. One such technique is passive acoustic monitoring, which is commonly coupled with automatic identification of animal species based on their sound. Automated sound analyses usually require the training of sound detection and identification algorithms. These algorithms are based on annotated acoustic datasets which mark the occurrence of sounds of species inside sound recordings. However, compiling large annotated acoustic datasets is time-consuming and requires experts, and therefore, they normally cover reduced spatial, temporal, and taxonomic scales. This data paper presents WABAD, the World Annotated Bird Acoustic Dataset for passive acoustic monitoring. WABAD is designed to provide the public, the research community, and conservation managers with a novel and globally representative annotated acoustic dataset. This database includes 5047 min of audio files annotated to species-level by local experts with the start and end time and the upper and lower frequencies of each identified bird vocalization in the recordings. The database has a wide taxonomic and spatial coverage, including information on 91,931 vocalizations from 1192 bird species recorded at 72 recording sites in 29 recording locations (mainly countries) and distributed across 13 biomes. WABAD can be used, for example, for developing and/or validating automatic species detection algorithms, answering ecological questions, such as assessing geographical variations on bird vocalizations, or comparing acoustic diversity indices with species-based diversity indices. The dataset is published under a Creative Commons Attribution 4.0 International license that permits redistribution and reuse on the condition that the original work is properly credited.

Dispersal is one of the most important aspects of animal behavior and can have far-reaching consequences for organismal ecology and evolution. Despite recent theoretical advances in understanding why individuals within the same population vary in dispersal behavior, relatively few studies have empirically evaluated the long-term causes and consequences of variable dispersal within natural populations. In this study, we used life history data collected over the course of 16 years to examine fitness outcomes in 867 known-age female tree swallows breeding in New York, USA, that differed in their dispersal status: “immigrant” females, defined as dispersers that hatched elsewhere, and “local” females, defined as non-dispersers that hatched within the study site and returned there after migration to breed. We also compared the life history responses of immigrant and local females to natural variation in weather, nest predation risk, and social environment at their breeding site. Local females were more likely to produce fledglings that recruited into the study area as adults. We also found several instances in which dispersal status interacted with an environmental metric to influence relative fitness, and these responses were largely consistent across life history measures. Overall, immigrant females were relatively resilient to variation in their extrinsic environment, while local females were highly sensitive to environmental conditions at the breeding site, performing relatively well when conditions were benign and faring relatively poorly as conditions became more stressful. We found little evidence that distance dispersed within a study site impacted female fitness, suggesting that the dispersal-associated differences in fitness that we observed operate mostly across broader spatial scales. Future work should undertake the direct and simultaneous measurement of behavior, physiology, and fitness of immigrant and local females across environmental contexts and should seek to understand whether and how context-dependent fitness variation of dispersers and non-dispersers scales up to influence larger ecological and evolutionary processes.

Global change is causing a widespread redistribution of species, and novel species are expected to impact populations in their recipient communities. Theory from invasion biology provides a framework to predict the impacts of range-shifting species. Specifically, the impacts of invasive predators are expected to be nonlinear (greatest per capita effects at low densities) and to be greater in their invaded ranges when compared to their historical ranges. For range-shifting species, we hypothesized that impacts would similarly be nonlinearly related to abundance and that impacts in the expanded range would be greater than those in the historical range (due to prey naivety and/or enemy release). Our alternative hypothesis was that impacts would be consistent between historical and expanded ranges (due to the potential for historical coevolutionary interactions with species in the expanded range). To test the applicability of this framework with range-shifting species, we conducted observational surveys and manipulative experiments in the historical and expanded ranges of two predators undergoing poleward expansions, the whelks Acanthinucella spirata and Mexacanthina lugubris. We assessed impacts on prey (acorn barnacles and mussels) abundance and community diversity and compared per capita impacts between regions. As with non-native invasive species, we found that both whelks reduced the abundance of prey species; however, our results supported a linear relationship and no decrease in per capita effect on prey with increasing density of the shifting predator, and we did not observe consistent impacts of range-shifting whelks on community diversity. Finally, impacts in whelks' expanded ranges were generally consistent with those in historical ranges, with some potential for increased impact in the expanded range. By adapting invasion frameworks, our work revealed that abundance and impacts in the historical range are indicators of range-shift impacts that could inform anticipatory management responses to range shifts.

Temperature responses of many biological traits—including population growth, survival, and development—are described by thermal performance curves (TPCs) with phenomenological models like the Briere function or mechanistic models related to chemical kinetics. Existing TPC models are either simple but inflexible in shape or flexible yet difficult to interpret in biological terms. Here we present flexTPC, a model that is parameterized exclusively in terms of biologically interpretable quantities: the thermal minimum, optimum, and maximum, the peak trait value, and thermal breadth. FlexTPC can describe unimodal temperature responses of any skewness and thermal breadth, enabling direct comparisons across populations, traits, or taxa with a single model. We apply flexTPC to various microbial and entomological datasets, compare results with the widely used Briere model, and find that flexTPC often has better predictive performance. The interpretability of flexTPC makes it ideal for modeling how thermal responses change with ecological stressors or evolve over time.

Forest pests pose critical threats to forest ecosystems worldwide, yet accurately predicting their spatial spread remains challenging due to complex dispersal behaviors, weather effects, and the inherent difficulty of tracking small organisms across large landscapes. These challenges have resulted in divergent estimates of typical dispersal distances across studies. Here, we use high-quality data from helicopter and field-crew surveys to parameterize dispersal kernels for the mountain pine beetle, a destructive pest that has recently expanded its range into Alberta, Canada. We find that fat-tailed kernels—those which allow for a small number of long-distance dispersal events—consistently provide the best fit to these data. Specifically, the radially symmetric Student's t-distribution with parameters $��\rho �=�0.012�$ km and $��\nu �=�1.45�$ stands out as parsimonious and user-friendly; this model predicts a median dispersal distance of 60 m, with the $��95�\mathrm{th}�$ percentile of dispersers traveling nearly 5 km. The best-fitting mathematical models have biological interpretations. The Student's t-distribution, derivable as a mixture of diffusive processes with varying settling times, is consistent with observations that mountain pine beetle adults fly short distances while few travel far; early-emerging beetles fly farther; and larger beetles from larger trees exhibit greater variance in flight distance. This phenotypic variability is mirrored in other forest pests, resulting in a stratified dispersal pattern where most individuals disperse locally while rare long-distance “jumpers” drive range expansion. Our approach demonstrates how aerial survey data can be used to characterize dispersal patterns, as many insects create diagnostic signatures—combining foliage damage patterns and host-tree preferences—that are visible from above. Since aerial surveys of North American forests are widely available, our methodology can be broadly used to create parsimonious dispersal models for many forest insects.

To contribute to our growing understanding of the urban ecological filtering process in highly biodiverse regions, we conducted a study on bird species assemblages across the landscape of Medellín and its surrounding areas in the Colombian Andes. Nonurban land cover categories included well-preserved and second-growth forests, exotic-tree plantations, and open areas. Urban areas were categorized into four urbanization levels ranging from 0% to 100% built cover at intervals of 25%. Well-preserved and second-growth forests exhibited the highest bird species richness, followed by open areas, while the 76%–100% urbanization level displayed the lowest richness. Based on either taxonomic or functional composition, the bird assemblages across all urbanization levels resembled open areas. The other nonurban land cover categories shared a lower proportion of bird species with open areas and all urbanization levels, with well-preserved forests showing distinct compositions. These results suggest that bird species inhabiting open areas face a broad urban ecological filtering until reaching a threshold above 75% built cover, while birds inhabiting well-preserved forest face a narrow ecological filtering at the urban edge. Our findings provide insights into urban ecological filtering at the landscape scale and pose significant challenges for urban planners aiming to maintain favorable environmental conditions for highly biodiverse species pools.

Complex landscapes are challenging to study because both the higher level contextual and interacting lower level mechanistic processes underpinning their ecological characteristics occur simultaneously. However, food-web structures can provide process insight in such landscapes by identifying these processes in specific contexts. Here, we used stable isotopes to identify spatially separate resources and infer resource flows underpinning food-web structures in a braided river. We found that river resources used by mobile consumers, including birds and fish, were spatially heterogeneous. Consumer resource use was related to four key structural food-web attributes: (1) spatiotemporal variation in foraging, (2) subsidies, (3) omnivory, and (4) ontogenetic niche shifts. Thus, both physical heterogeneity (contextual physical processes) and adaptive characteristics of consumers (mechanistic processes) were likely contributing to important food-web structures. Identifying these food-web structures in landscapes, across scales of resource use and spatial distribution, provides a way to identify processes and scales likely contributing to food-web stabilization.