Ecology Letters最新文献

Evolutionary change within community members and shifts in species composition via species sorting contribute to community and trait dynamics. However, we do not understand when and how both processes contribute to community dynamics. Here, we estimated the contributions of species sorting and evolution over time (60 days) in bacterial communities of 24 species under selection by a ciliate predator. We found that species sorting contributed to increased community carrying capacity, while evolution contributed to decreased anti-predator defences. The relative roles of both processes changed over time, and our analysis indicates that if initial trait variation was in the direction of selection, species sorting prevailed, otherwise evolution drove phenotypic change. Furthermore, community composition, population densities and genomic evolution were affected by phenotypic match–mismatch combinations of predator and prey evolutionary history. Overall, our findings help to integrate when and how ecological and evolutionary processes structure communities.

Isolation caused by anthropogenic habitat fragmentation can destabilize populations. Populations relying on the inflow of immigrants can face reduced fitness due to inbreeding depression as fewer new individuals arrive. Empirical studies of the demographic consequences of isolation are critical to understand how populations persist through changing conditions. We used a 34-year demographic and environmental dataset from a population of cooperatively breeding Florida Scrub-Jays (Aphelocoma coerulescens) to create mechanistic models linking environmental and demographic factors to population growth rates. We found that the population has not declined despite both declining immigration and increasing inbreeding, owing to a coinciding response in breeder survival. We find evidence of density-dependent immigration, breeder survival and fecundity, indicating that interactions between vital rates and local density play a role in buffering the population against change. Our study elucidates the impacts of isolation on demography and how long-term stability is maintained via demographic responses.

Identifying the scaling rules describing ecological patterns across time and space is a central challenge in ecology. Taylor's law of fluctuation scaling, which states that the variance of a population's size or density is proportional to a positive power of the mean size or density, has been widely observed in population dynamics and characterizes variability in multiple scientific domains. However, it is unclear if this phenomenon accurately describes ecological patterns across many orders of magnitude in time, and therefore links otherwise disparate observations. Here, we use water clarity observations from 10,531 days of high-frequency measurements in 35 globally distributed lakes, and lower-frequency measurements over multiple decades from 6342 lakes to test this unknown. We focus on water clarity as an integrative ecological characteristic that responds to both biotic and abiotic drivers. We provide the first documentation that variations in ecological measurements across diverse sites and temporal scales exhibit variance patterns consistent with Taylor's law, and that model coefficients increase in a predictable yet non-linear manner with decreasing observation frequency. This discovery effectively links high-frequency sensor network observations with long-term historical monitoring records, thereby affording new opportunities to understand and predict ecological dynamics on time scales from days to decades.

Ecological interactions are foundational to our understanding of community composition and function. While interactions are known to change depending on the environmental context, it has generally been assumed that external environmental factors are responsible for driving these dependencies. Here, we derive a theoretical framework which instead focuses on how intrinsic environmental changes caused by the organisms themselves alter interaction values. Our central concept is the ‘instantaneous interaction’, which captures the feedback between the current environmental state and organismal growth, generating spatiotemporal context-dependencies as organisms modify their environment over time and/or space. We use small microbial communities to illustrate how this framework can predict time-dependencies in a toxin degradation system, and relate time- and spatial-dependencies in crossfeeding communities. By re-centring the relationship between organisms and their environment, our framework predicts the variations in interactions wherever intrinsic, organism-driven environmental change dominates over external drivers.

Ecological restoration is a leading approach to mitigating biodiversity decline. While restoration often leads to an immediate increase in species abundance or diversity, it is rarely clear whether it supports longer-term biodiversity gains at the landscape scale. To examine the impacts of urban restoration on pollinator biodiversity, we conducted a 3-year natural experiment in 18 parks across a large metropolitan area. We applied an occupancy model to our survey data to determine how restoration, woody plant density and pollinator specialisation impacted interannual pollinator metacommunity dynamics. Restoration drove a rapid increase in pollinator species occurrence that was maintained through a positive balance between colonisation and persistence, resulting in pollinator species richness gains that are retained. We conclude that urban restoration can effectively conserve pollinator biodiversity by influencing the processes that underlie long-term population stability. Our results highlight the need to study the long-term effects of restoration in different landscape contexts.

Ecosystems are substantially changing in response to ongoing climate change. For example, coral reefs have declined in coral dominance, with some reefs undergoing regime shifts to non-coral states. However, reef responses may vary through multiple heat stress events, with the rarity of long-term ecological datasets rendering such understanding uncertain. Assessing coral reefs across the inner Seychelles islands using a 28-year dataset, we document faster coral recovery from the 2016 than the 1998 marine heatwave event. Further, compositions of benthic and fish communities were more resistant to change following the more recent heat stress, having stabilized in a persistent altered state, with greater herbivory, following the 1998 climate disturbance. Counter to predictions, a macroalgal-dominated reef that had regime-shifted following the 1998 disturbance is transitioning to a coral-dominated state following the 2016 heat stress. Collectively, these patterns indicate that reef systems may be more resilient to repeat heatwave events than anticipated.

Forecasting population responses to rapidly changing marine ecosystems requires mechanistic models integrating complex demographic processes, fitted to long time series, across large spatial scales. We used a Bayesian metapopulation model fit to colony census data and climatic covariates spanning 1900–2100 for all Northeast Atlantic colonies of an exemplar seabird, the Northern gannet (Morus bassanus) to investigate metapopulation dynamics under two climate scenarios. Fecundity varied non-linearly with near-surface air temperature and recruitment was depressed by sea surface temperature. We predict regime changes in density dependence as marine carrying capacities become constrained with increasing SST. Sensitivity to climate change varied across space and time, disadvantaging southwestern colonies whilst benefitting northern ones. Such sensitivity is noteworthy for a species previously assumed robust to climate change. We provide a spatial overview of climate sensitivities across a metapopulation to help with evidence-based conservation management and open the way for similar mechanistic explorations for other colonial species.