Meeting Abstract
Hybridization during species invasions may yield a variety of evolutionary results – from increasing reproductive isolation to fusion of the hybridizing populations, resulting in a well-mixed population or primarily replacement of one population by the other. However, the dynamic period of this process may be relatively transient, offering few opportunities for observation. We are investigating this transient stage of the ongoing invasion of the invasive rusty crayfish (Orconectes rusticus) into the native range of the congeneric Sanborn’s crayfish (Orconectes sanbornii) in the Huron River in north-central Ohio. Yearly surveys (2010 to 2015) along the river’s length reveal a relatively stable gradient in the ratio of native to invasive morphospecies: the most upstream sites most resemble the morphology of the native species while the furthest downstream sites exhibit morphology consistent with the invasive species. This spatial pattern of species abundance is surprisingly stable, possibly influenced by seasonal patterns of precipitation on streamflow; future changes to patterns of annual precipitation may alter this dynamic. Sites where both morphospecies are caught also reveal morphological intermediates and hybridization at two such sites has been confirmed with mitochondrial and allozyme markers. Recently, we have developed microsatellite markers for both species, giving us greater resolution into the population genetics of these taxa. Here, we examine the pattern of morphological and genotypic change at ten sites sampled throughout the Huron River watershed to further characterize the influences of hybridization and watershed structure in this ongoing species invasion.
