Angela Roles
We are studying the invasion of the rusty crayfish (Orconectes rusticus) into the range of Sanborn’s crayfish (O. sanbornii) in Ohio. The rusty crayfish is well known as an invasive species, notable for its displacement of O. propinquus in much of the Midwest. We have sampled rivers in which both rusty and Sanborn’s crayfish coexist, as well as rivers that contain only one of the species (within each species’ native range). Using microsatellite markers, we estimate population genetic parameters (heterozygosity, allele numbers, and percent polymorphic loci) for each species inhabiting its native range and for rivers containing both species. We also calculate sex ratios and size data for each site. Multiple sites within a watershed allow us to examine patterns of sympatry: the native species tends to have higher relative numbers at upstream sites while the invasive rusty crayfish dominates downstream channels. Molecular markers, with genotype patterns that differ between species, are used as indicators of hybridization between the native and invasive crayfishes.
Keywords: CRAYFISH, ORCONECTES RUSTICUS, ORCONECTES SANBORNII, HYBRIDIZATION, MICROSATELLITE
