SREL Reprint #1880

Cytonuclear genetics of experimental fish hybrid zones inside Biosphere 2

Kim T. Scribner1 and John C. Avise2

1Alaska Fish and Wildlife Research Center, National Biological Survey, 1011 East Tudor Road. Anchorage, AK 99503
2Department of Genetics, University of Georgia, Athens, GA 30602

Abstract: Two species of mosquitofish (family Poecilidae) known to hybridize in nature were introduced into freshwater habitats inside Biosphere 2, and their population genetics were monitored after 2 years. Within four to six generations, nuclear and cytoplasmic markers characteristic of Gambusia holbrooki had risen greatly in frequency, although some Gambusia affinis alleles and haplotypes were retained primarily in recombinant genotypes, indicative of in introgressive hybridization. The temporal cytonuclear dynamics proved similar to population genetic changes observed in replicated experimental hybrid populations outside of Biosphere 2, thus indicating strong directional selection favoring G. holbrooki genotypes across the range of environments monitored. When interpreted in the context of species-specific population demographies observed previously, results suggest that the extremely rapid evolution in these zones of secondary contact is attributable primarily to species differences in life-history traits.

SREL Reprint #1880

Scribner, K.T. and J.C. Avise. 1994. Cytonuclear genetics of experimental fish hybrid zones inside Biosphere 2. Proceedings of the National Academy of Science 91:5066-5069. 

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).