Rates and patterns of evolutionary change in human altered ecosystems

Background/Question/Methods

Evolution was traditionally thought to be very slow, occurring only on the time frame of thousands to millions of years. Recent work, however, has shown that appreciable evolution can occur after only decades to centuries. This “contemporary evolution” is associated with several kinds of environmental disturbance, including invasive species, climate change, hunting/harvesting, pollution, and range expansion. We ask what types of disturbances are associated with the most rapid phenotypic changes – and what factors might be responsible for the differences. We address these topics through a Bayesian meta-analysis of thousands of rates of phenotypic change recorded in hundreds of studies of plants and animals in nature.

Results/Conclusions

Previous analyses of an earlier version of the database suggested that rates of phenotypic change are higher in human-disturbed situations than in more “natural” contexts. Those analyses also suggested that rates of change in human-disturbed situations are greatest when the disturbances involve humans acting as predators: i.e., hunting or harvesting. By contrast, rates of change do not appear especially high for invasive species. We re-evaluate these conclusions using our much larger and more comprehensive database in a meta-analytic framework that explicitly accounts for uncertainty. We also consider how phenotypic changes are shaped by genetic change (evolution), environmental induction (plasticity), and their combination. And we consider what types of traits (e.g., life history, morphology, behavior) show the greatest rates of change. Finally, we consider how these phenotypic changes are likely to shape ecological process, such as population persistence (evolutionary rescue), community structure, and ecosystem function.