Does Position Along the Watershed Affect Hybridization Dynamics Between the Native OrconectesSanbornii and Invasive O. Rusticus?

Science Center, Bent Corridor

The rusty crayfish (Orconectes rusticus), has been recorded to have expanded outside of its endemic range of Southwest Ohio and Kentucky, displacing a variety of native crayfish (Butler and Stein 1985). O. rusticus range expansion is likely due to human use as live bate, resulting in its introduction in the native range of the Sanborn’s crayfish (O. sanbornii) (Butler and Stein 1985). We are investigating the morphological and genetic impacts of invasion and possible hybridization in two invaded watersheds in north-central Ohio. Crayfish were collected from multiple sites along the Kokosing River and the Huron River. In both rivers, the fraction of sampled crayfish identified as invasive versus native varies with position in the watershed with a higher proportion of invaders downstream than upstream. Here, we ask whether the genetic composition of populations sampled along the watershed agrees with the morphological pattern, using data from mitochondrial genes and nuclear microsatellite loci. Further, hybridization has been confirmed in the Huron R. (Zuber et al. 2012) but not yet in the Kokosing R. A closer look at the distribution of genetic diversity along the length of the watershed may provide insight into the consequences of the invasion for both invader and native.