An ecological tardis: the implications of facilitation through evolutionary time.

It is often challenging to link ecological processes to evolution because different temporal scales are studied and necessarily inferred. In a recent paper by Valiente-Banuet et al., Quaternary plant taxa are shown to 'pull' more ancient Tertiary taxa through evolutionary time by facilitation. This finding has profound implications for population and community ecology. Positive species interactions are of wider importance than was assumed previously in determining community composition by enhancing long-term biodiversity, mediating climate change and providing an interdependent set of selection processes in addition to the environment. Future experiments should consider the evolutionary history of species, manipulate species interactions explicitly to test for environmental effects and re-evaluate the adaptive significance of traits in the context of other species.