Status of the stippled studfish Fundulus bifax, a killifish endemic to the Tallapoosa River basin, USA

Abstract

The stippled studfish Fundulus bifax, which is endemic to the Tallapoosa River system of Alabama and Georgia, USA, has been considered at risk due to habitat degradation. Requisite habitat for this species is clean water over clean sand in small or large streams. F. bifax is apparently extirpated in Georgia, and appears increasingly uncommon in Alabama. This has resulted in a global ranking of N2N3, imperiled/vulnerable, from NatureServe. In 2008, 24 Tallapoosa River drainage sites in Alabama were visited in an effort to document the current status of this species. Many of these were locations where the fish has been collected since 1980, as documented in the University of Alabama Ichthyology Collection. At least 1 individual was found in each of 6 different creek systems in Coosa, Elmore, Randolph, and Tallapoosa Counties. This is a contraction of what has been considered this species' range, and appears to be the result of habitat degradation. To examine genetic variation between existing populations, and between 2 closely related species, 852 bases of the mitochondrial cytochrome b gene of 10 individuals were compared through neighbor-joining and Bayesian tree building, and through calculating genetic distance, D. Both analyses showed existing populations of F. bifax to be monophyletic, with low genetic variation between them. Neither of its putative closest relatives, F. catenatus and F. stellifer, was found to be more closely related to F. bifax. The future of the species is in doubt, with 6 disjunct populations being vulnerable to further habitat degradation and diminished gene flow.