The extent of introgression outside the contact zone between Notropis cornutus and Notropis chrysocephalus (Teleostei: Cyprinidae)

Abstract

These two species hybridize in a long, narrow zone in the midwestern USA. To quantify the extent of introgression of genetic markers outside of this zone, samples were collected among transects starting near the region of contact, followed by samples progressively more distant. Introgressed mtDNA and allozyme haplotypes were rare and found only in the population closest to the contact zone. Introgressed haplotypes are probably indicators of a more southern position of the contact zone during the Pleistocene, with the contact zone shifting northward with the recession of the glacial front. -from Authors