Cytochrome b sequence variation in the crystal darter Crystallaria asprella (Actinopterygii : Percidae)

Crystallaria asprella, sole member of the genus Crystallaria, was distribut ed throughout much of the eastern United States but today persists only in isolated populations. We quantified genetic variation among remaining popul ations of C. asprella by sequencing the mitochondrially encoded cytochrome (cyt b) gene in 24 individuals from fire sample localities. Phylogenetic an alysis of these samples and individuals from eight other darter species, Pe rca, Gymnocephalus, Stizostedion, and Zingel, resulted in 80 equally most-p arsimonious trees, Four of the five populations of C. asprella were monophy letic in all trees. Monophyly of the population from the Cahaba River was s upported in 60 of 80 most-parsimonious trees. In the remaining 20 trees, on e individual from the Cahaba River was included in a trichotomy with a clad e of the other individuals from the Cahaba River and a clade of individuals from the Pearl River, The overall pattern of relationships among populatio ns of C, asprella was (Elk River, WW (Saline River, AR (Zumbro River, MN (C ahaba River, AL, Pearl River, L4)))). The most divergent population of C. a sprella is from the Elk River in West Virginia. In spite of considerable co llecting effort, only five individuals have been collected from the Elk Riv er since 1987, Crystallaria asprella from the Elk River differ from other p opulations by 11.2-11.8% sequence divergence, Their continued existence is currently threatened by logging, coal milling, and natural pas exploration. Our data document a distinct evolutionarily significant unit in the Elk Ri ver that likely is in great peril and should be protected under the U,S, En dangered Species Act.