The mating system and gene dynamics of plateau pikas

Evolutionary theory suggests that mating systems should have substantial ef fects on gene dynamics of local populations. In polygynous species, local ' breeding groups' may produce significant genetic structure, due to genetic differences among groups, and rate of loss of genetic variation from such p opulations may be considerably slowed. We examined possible influences of t he variable mating system and family group structure on genetic properties of a population of plateau pikas (Ochotona curzoniae). Pika gene dynamics w ere examined via F-statistics and effective population sizes (N-e), calcula ted from genetic correlations within and among individuals and families. Ge netic correlations were estimated from mating patterns, population demograp hy, and dispersal patterns. Substantial genetic structure within the popula tion was indicated by a strongly positive F-LS. Genetic influence of natal dispersal out of pika families was indicated by a strongly negative inbreed ing statistic (F-IL = -0.34). Effective size of the population was not grea tly different from the census population, whereas a traditional estimate of effective size of the population was much lower, indicating that the famil y structure of the pikas results in a slowed loss of genetic variation over time. Thus, even though mating patterns of plateau pikas were variable, fa mily structure had a strong influence on pika gene dynamics. (C) 2000 Publi shed by Elsevier Science B.V. All rights reserved.