Ecology Letters最新文献

The determinants of population variability across taxa, time, and space are not fully understood, particularly for insects, a group with recent reports of widespread abundance declines. We collated data from unpublished and published sources to calculate indices of interannual population variability for over 4500 unique insect time series, comprising data from nearly 1500 species. We evaluate whether insects exhibit greater population variability than other types of animals. Our results demonstrate that insects as a group indeed exhibit much greater population variability than birds, mammals, or fish, but that within Insecta, included orders show similar levels of population variability. We also find that population variability in insects is greater at higher latitudes, for species with smaller body sizes and for shorter, older time series and that it varies between biomes. Overall, our findings can inform the interpretation and prediction of insect population trends, fluctuations and extinction risk in an era of insect decline.

Data synthesised and published as response ratios in ecology ( $\text{lnRR}$ , or ratio of means, $\mathrm{RoM}$ ) remain isolated from broad secondary analyses because they cannot be converted to other effect size metrics. Here I address this lack of data interoperability by developing a conversion to the widely used Hedges' $d$ (standardised mean difference, $\mathrm{SMD}$ ). This conversion is practical and near exact-as long as assumptions of homogeneity of variances are met, Hedges' $g$ correction is used to adjust for small-sample bias, and only additive and not multiplicative ecological processes are converted. I then generalise this conversion with abstract algebra to develop additional opportunities to reuse effect sizes-first by stating the response ratio as a geometric construction of Pythagorean means, and then $d$ as a proportional compass-and-straightedge construction of the response ratio. Constructability is a new pathway of interoperability for effect sizes, and without collecting new data, allows for the response ratio and $d$ to be repurposed into relative change datatypes such as the arithmetic, harmonic, geometric, quadratic and logarithmic means. Much of what has been synthesised in ecology is only available as response ratios, and I hope these conversions increase their value post-publication and facilitate reuse for bolder, more comprehensive meta-analyses.

Modern Coexistence Theory (MCT) has long aimed to predict community structure, but empirical support remains scattered across unconnected case-studies from a narrow subset of systems where it is possible to quantify niche and fitness differences (e.g., pairwise interactions between fast-growing plants or protists). We sought a framework to apply MCT to a broader range of ecological scenarios by combining eDNA dietary data with life-history traits of mammal herbivores from diverse communities across three African savannas. Although this first application of the framework treated dietary niche differentiation as the sole mechanism for coexistence, it unveiled three conclusions about multispecies coexistence. First, dietary niche differentiation promoted coexistence but was insufficient to explain observed coexistence for all species. Second, modelled coexistence patterns in herbivore communities could not be predicted from species-level traits or pairwise comparisons. Third, herbivore diversity is generally robust to reductions in the number of plant resources, particularly when there is more dietary specialisation.

Stability selection is the process by which species are lost from a community due to a structural susceptibility to extinction. Stability selection is non-adaptive because it does not lead to the evolution of traits that increase individual fitness. However, stability selection could still drive evolutionary change because the stability of populations is linked to heritable traits. Here we demonstrate both phenomena with a live predator-prey system. We show that the stability properties of a predator-prey pair vary with prey genetics, indicating the potential for differential extinction to influence the genotypic makeup of populations. Second, we show that the loss of unstable predator-prey pairs in subpopulations from the overall population can lead to trait evolution in the aggregate population, providing empirical support for the stability selection mechanism. Our results indicate that community-level processes such as predator-prey interactions can generate eco-evolutionary change at the population scale.

Although habitat area and isolation are considered key factors influencing plant disease and herbivory, their specific mechanisms remain underexplored within island biogeography. We investigated the direct and indirect effects (via community functional traits) of island area and isolation on plant disease and herbivory across 21 tropical islands in the South China Sea. Community-weighted mean leaf area (CWM LA) was the most significant functional predictor at the community level. Decomposing CWM LA revealed isolation primarily drove species turnover (LA_STE; 99.99% of the relative explanatory power), whereas area mainly influenced intraspecific variation (LA_ITV; 60.42% of the relative explanatory power). Isolation-mediated species turnover indirectly amplified disease and herbivory, likely through adaptive trait shifts favouring resource acquisition. Island area had no significant effect on disease and herbivory at the community level. This study reveals the complex roles of area and isolation in plant biotic risks, underscoring the utility of island biogeography theory.