PUB - Publikationen an der Universität Bielefeld

Motivated by present activities in (statistical) physics directed towardsbiological evolution, we review the interplay of three evolutionary forces:mutation, selection, and genetic drift. The review addresses itself tophysicists and intends to bridge the gap between the biological and thephysical literature. We first clarify the terminology and recapitulate thebasic models of population genetics, which describe the evolution of thecomposition of a population under the joint action of the various evolutionaryforces. Building on these foundations, we specify the ingredients explicitly,namely, the various mutation models and fitness landscapes. We then reviewrecent developments concerning models of mutational degradation. These predictupper limits for the mutation rate above which mutation can no longer becontrolled by selection, the most important phenomena being error thresholds,Muller's ratchet, and mutational meltdowns. Error thresholds are deterministicphenomena, whereas Muller's ratchet requires the stochastic component broughtabout by finite population size. Mutational meltdowns additionally rely on anexplicit model of population dynamics, and describe the extinction ofpopulations. Special emphasis is put on the mutual relationship between thesephenomena. Finally, a few connections with the process of molecular evolutionare established.