Studies of Adaptive Radiation Using Model Microbial Systems.

Adaptive radiation is a fundamental process in the evolution of biodiversity. The effects of seasonality, resource partitioning, and spatial heterogeneity have been examined experimentally using evolving populations of microbes. In all environmental conditions examined, ecological interactions have large effect on the likelihood and outcome of adaptive radiation. Adaptive radiation in seasonal environments can arise because of demographic trade-offs and excretion of metabolites. Resource partitioning can occur even in the absence of temporal or spatial heterogeneity. Spatial heterogeneity arising via growth is sufficient to generate microenvironments and subsequent adaptive radiation. However, ecological interactions maintaining diversity can be sensitive to slight alterations of the environmental conditions. Laboratory populations of microbes are ideal model systems to test the factors essential for adaptive radiation.