SYMMETRICAL HYBRIDIZATION BETWEEN BLACK CRAPPIE AND WHITE CRAPPIE IN AN ALABAMA RESERVOIR BASED ON ANALYSIS OF THE CYTOCHROME-B GENE

Natural hybridization between black crappie Pomoxis nigromaculatus and white crappie P. annularis recently has been documented in reservoirs of the southeastern United States, including Weiss Reservoir in Alaba ma. In this study, we examined hybrid zone dynamics of crappies in Wei ss Reservoir using allozymes and restriction fragment length polymorph isms of the cytochrome-b region in mitochondrial DNA (mtDNA) to (1) de termine the maternal parent of F-1 hybrid crappies in this reservoir a nd (2) compare levels of mtDNA gene flow in this hybrid zone with thos e from other hybrid zones. We found that hybridization was reciprocal between the two crappie species. In addition, the percentage of F-1 hy brids with white crappie as their maternal parent was not significantl y different (P > 0.10) from the expected value based on abundances of each parental species in Weiss Reservoir. Past studies of mtDNA gene f low in hybrid zones found that hybridization was unidirectional. Thus, results of this study suggest that current hypotheses on mtDNA gene f low in hybrid zones are not universally correct or that the crappie hy brid zone in Weiss Reservoir is an atypical outcome of habitat change (impoundment of the Coosa River).