Genetic Evidence for Naturally Occuring Fertile Hybrids Between Two Goby Species, Pomatoschistus minutus and P. Ioszanoi (Pisces, Gobiidae)

Abstract

Sympatric populations of the closely related sand goby species P. minutus and P. lozanoi were examined electrophoretically. Of 33 protein loci resolved, 3 were completely species diagnostic and 1 was virtually so. In samples containing, in all, 1051 P. minutus and 604 P. lozanoi, 5 individuals with a hybrid genotype at all these loci were found. One fish of unusual genotype at these 4 loci was discovered. On the criterion of the distribution of the alleles at these 4 loci the probability that this fish is an F1 hybrid is < 5 .times. 10-6; that it is a backcross, only slightly higher. This individual is most likely an F2 resulting from a cross between 2 F1 individuals.