Hybridization between Chrosomus erythrogaster and Notropis cornutus (Pisces: Cyprinidae)

Hybrids between the southern redbelly dace, Chrosomus erythrogaster and the common shiner, Notropis cornutus have been found in Rickelson Creek, Lee County, Illinois. Meristic and morphometric analysis of 30 N. cornutus, 30 C. erythogaster, and 14 hybrids has shown that the hybrids are most likely Fl's and that they are not intermediate between the parents in all characters. Karyotype analysis has shown that both parents have a diploid number of 50, but that they differ in the ratio of metacentric, and submetacentric pairs. The F1 hybrids combine the two parental genomes. A discussion of the causes of hybridization is presented.