Mechanisms maintaining genetic and phenotypic variation in natural populations are central issues in ecology and evolution. However, the long generation times of most organisms and the complexity of natural environments have made elucidation of ecological and evolutionary mechanisms difficult. Experiments using bacterial populations propagated in controlled environments reduce ecosystem complexity to the point where understanding simple processes in isolation becomes possible. Recent studies reveal the circumstances and mechanisms that promote the emergence of stable polymorphisms.
Bibliographical noteFunding Information:
The authors thank K. McCallum and J. Pannell for valuable discussion, and Danny Rozen and Peg Riley for sharing unpublished data. This work is supported by grants from the BBSRC (UK), NERC (UK), NSERC (Canada) and The British Council.