Population genetic structure of the introduced signal crayfish (Pacifastacus leniusculus) in 15 Sierra Nevada, USA, lakes

S.A. Roark, D.C. Sternberg, and S.I. Guttman. Department of Zoology, Miami University, Oxford, OH 45056

To determine whether genetic patterns in populations of the introduced signal crayfish (Pacifastacus leniusculus) were related to anthropogenic influences, populations were sampled from 15 Sierra Nevada lakes and reservoirs, including three sites on Lake Tahoe, representing a range of anthropogenic influences and lake morphologies in three isolated drainage systems. Starch gel electrophoresis was used to determine allelic frequencies at three polymorphic loci. We predicted that population genetic patterns would reflect natural influences, particularly geographic isolation, but might also reflect human impacts (development and/or recreational usage) or hydrologic regime (reservoirs vs natural lakes). Our results revealed limited genetic structure within and among populations, and some regional patterns in allelic distributions. Genetic distance was not related to geographic distance, and neither allelic frequencies nor genetic diversity appeared related to hydrologic regime or human impact. The lack of a strong relationship between genetic and geographic patterns suggests the observed genetic structure results from a mechanism such as dispersal by human transport of crayfish as bait rather than from natural dispersal via stream corridors. Additional analyses using AFLPs and microsatellites currently in progress may be useful in discerning patterns not apparent in our survey of enzymatic loci.