Allozyme analysis of the hybrid Phoxinus eos × Phoxinus neogaeus (Pisces: Cyprinidae) in Nebraska

Abstract

Twenty-three fish from two localities in Nebraska were electrophoresed for three marker loci that distinguish Phoxinus eos and P. neogaeus. Seven had patterns of pure P. eos and 16 were heterozygous at all three markers. Of these, two were morphologically similar to P. eos, while the rest more closely resembled neogaeus. All hybrids were female. Two hypotheses are suggested: (1) The F1 hybrids fall into two morphological groups, dependent on the species of the maternal progenitor and (2) the hybrids are a parthenogenetic species. No introgression was detected in this study and the question of hybrid reproduction remains unresolved.