Organisms as Complex Structures Wrapped in a Complex Web of Life.

AbstractA pressing issue is to understand how biological complexity impacts the persistence and adaptation of populations. Natural environments are under unprecedented pressure as a result of climate change and land use change, which makes biological populations and ecological communities vulnerable. Evolution by natural selection-that is, genetic change in response to selection-is one important way species can cope with such changes. Selection often operates on complex traits, and much of selection is due to ecological interactions that, in turn, often form complex networks of species. In this sense, ecological interactions play a dual role: ecological interactions are essential to guarantee the resilience of communities and the functioning of ecosystem services, and they are a source of selection that shapes complex traits. The development of a new integrative framework combining the complexity of selected traits with the complexity of interaction patterns is essential to address potential cascading effects and extinctions. Unfortunately, studies that focus on these two levels of complexity, whether using theoretical or empirical approaches, are still scarce. In this special feature, we bring together articles that contribute to bridging this gap in the study of species coevolution and the evolution of complex traits.