Hybridization between an invasive and a native species of the crayfish genus Orconectes in north-central Ohio

Abstract

Hybridization between native and invasive species is an important but little-studied factor in crayfish invasions, with few documented natural cases. Here, we report genetic evidence of hybridization between invasive O. rusticus (Girard, 1852) and native O. sanbornii (Girard, 1852) in the Huron River in north-central Ohio based on a combination of molecular markers: nuclear DNA, mitochondrial DNA, and allozymes. Although we found no fixed differences between the species at nuclear DNA loci, fixed differences in mtDNA and allozyme loci confirmed the presence of individuals of hybrid ancestry. We also found preliminary evidence of possible mitochondrial recombination and biparental inheritance (though the existence of rare haplotypes cannot be excluded at the present time). We examined morphological features of both species in sympatry and allopatry and confirmed species-diagnostic morphological features including gonopod traits and shape of the annulus ventralis. This study is the second to detect hybridization between O. rusticus and a congener, which suggests that this may be an important mechanism of invasion by O. rusticus when closely related species are present. Further study of this system, including more extensive sampling and additional molecular markers, is necessary to understand the extent and implications of hybridization for the native species.