SREL Reprint #2226

Downstream gene flow and genetic structure of Gambusia holbrooki (eastern mosquitofish) populations

Jose D. Hernandez-Martich and Michael H. Smith

Savannah River Ecology Laboratory, Drawer E, Aiken, SC 28902 and
Institute of Ecology, University of Georgia, Athens, GA 30602 USA

Abstract: Twelve populations of Gambusia holbrooki were sampled in three drainages of Florida and southern Georgia and their genetic structure was determined from the electrophoretic variation of 13 loci. There was less genetic variation (H = 0.199 vs. 0.242) and more differentiation within (D = 0.108 vs. 0.097) and among (D = 0.192 vs. 0.148) drainages in upstream than in downstream populations. Estimated levels of gene flow were lower (Nm = 1.2 vs. 2.5) among upstream than among downstream populations. Florida populations were genetically differentiated from those in Georgia (D = 0.184). This differentiation could result from the isolation of peninsular Florida and downstream gene flow after it rejoined the mainland.

Keywords: allozymes, biogeography, Gambusia holbrooki, gene flow, genetic differentiation, heterozygosity.

SREL Reprint #2226

Hernandez-Martich, J.D. and M.H. Smith. 1997. Downstream gene flow and genetic structure of Gambusia holbrooki (eastern mosquitofish) populations. Heredity 79:295-301.

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