Multispecies Hybridization among Native and Introduced Centrarchid Basses in Central Texas

Abstract

Allele-frequency differences at 11 polymorphic protein loci provided discrete genetic markers with which to estimate the extent of hybridization among native and introduced centrarchid basses in central Texas streams. Native Guadalupe bass Micropterus treculi and northern largemouth bass M. salmoides salmoides now coexist with introduced Florida largemouth bass M. s. floridanus and smallmouth bass M. dolomieui in these streams. Interspecific hybridization was detected in three of four populations from the Blanco and San Marcos rivers, hybrids making up at least 31.8% of the individuals sampled. Complex hybridization patterns were evident, because F₁, F₂, and backcross hybrids were detected. At least one individual exhibited genetic markers of largemouth, smallmouth, and Guadalupe bass. Extensive multispecies hybridization threatens the survival of the endemic Guadalupe bass.