Genetic Structure and Systematics of Smallmouth Bass, with Emphasis on Interior Highlands Populations

Abstract

We conducted an allozyme survey of genetic variation at 33 gene loci in smallmouth bass Micropterus dolomieu from 57 localities encompassing most of the range of the species, but with an emphasis (51 samples) on the Interior Highlands (Ozark and Ouachita uplands). Samples exhibited a moderate amount of total genic diversity (HT = 0.068), but high genetic heterogenity (FST = 0.383). Phylogenetic analyses supported recognition of three clades from the Interior Highlands: (1) the previously recognized Neosho smallmouth bass in Ozark tributaries of the middle Arkansas River; (2) the Ouachita smallmouth bass in the Little and Ouachita river drainages of the Ouachita Highlands; and (3) a clade that included populations from the White, Black, Missouri, and other streams in the northern and eastern Ozarks. This third clade was very similar to populations from the Ohio and upper Mississippi river basins, and, on the basis of allele frequency parsimony, more closely related to them than to the Neosho and Ouachita smallmouth basses. To preserve genetic diversity and the options that divergent native stocks represent for future management, stock transfers of smallmouth bass should take into account potential effects on native forms of the species.