Ecology最新文献

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.

Leaf herbivory is a ubiquitous ecological interaction that varies significantly in intensity across species, habitats, and biogeographic regions. Although quantification of leaf damage is crucial for understanding many ecological processes, the accuracy and precision of various damage estimation methods used by researchers, including visual estimation, digital image analysis, and artificial intelligence, have not been evaluated and compared. We use a phylogenetically diverse group of tropical plants to compare the accuracy and precision of damage estimation methods and use the results to provide a guide to herbivory estimation that balances the advantages and disadvantages of each method. We found that visual estimation tended to overestimate herbivory levels compared to digital methods but was 15 times faster and improved in accuracy and speed with training. Conversely, deep-learning algorithms underestimated herbivory relative to image analysis with ImageJ when it was on the margin, but showed similar accuracy for damage inside of leaf margins. Our results indicate that while visual methods allow for rapid assessment of large sample sizes and are suitable for detecting broad patterns of damage, image analysis is crucial for accurate and precise quantification. The disadvantages of each method, however, can be minimized through proper training and efficient use of each tool, and we therefore provide a guide of practical approaches to herbivory estimation.

Spatial pattern formation is recognized as a signal of ecological resilience, which could enhance ecosystems' persistence to environmental stress and make them evade catastrophic transitions. However, there is a lack of evidence and mechanisms for this phenomenon in natural ecosystems. Here, we conducted a large-scale plant community and spatial pattern survey across 116 sites in the alpine marshes on the eastern Tibetan Plateau. Our results showed that the alpine marsh shifted to a stable state characterized by multiple hummock characteristics during degradation. The hummock formation enhanced the compositional similarity between hummock-associated communities and the desired alpine marsh, thereby driving ecological resilience and making the system less susceptible to catastrophic transitions. Furthermore, an increase in hummock area and height, coupled with a reduction in hummock number, enhanced both environmental heterogeneity and plant beta diversity. In turn, greater environmental heterogeneity positively influenced beta diversity, which subsequently promoted higher compositional similarity across communities, ultimately contributing to increased ecological resilience. This study provides evidence and a mechanism for showing that spatial pattern formation drives resilience in real-world ecosystems. The findings highlight the necessity of incorporating spatial patterns into strategies for conserving biodiversity and ecosystem functioning, as well as enhancing ecological resilience in the face of accelerating environmental change.

A major challenge in invasion ecology is determining which introduced species pose a threat to resident species through competitive displacement. Since it is impossible to allocate management resources to preventing interactions among all resident and introduced species, methods for identifying instances of potential competitive displacement would greatly help focus precious management resources. Additionally, methods that use readily available data, such as species counts or functional traits, are especially advantageous under urgent invasion timelines compared to those requiring more time-intensive experimental data. Here, we provide a framework for estimating competition outcomes—including displacement—between resident and invading species using species count and functional trait data, two readily available data sources. Our framework provides methods for estimating displacement that is possibly in progress from species count data and estimating possible displacement from functional traits. We apply this framework to the native and introduced gecko species on the Caribbean island of Curaçao. Our work indicates a potential for the displacement of all three native species by introduced species and suggests that the displacement of one native species may already be underway. Given the urgency of the biodiversity crisis, our framework provides a usable tool for the early identification of potentially detrimental interactions from introduced species and provides insights to focus future studies and guide management efforts.