Genetic and meristic variations between and within populations of Etheostoma moorei (Yellowcheek darter)

Richard M. Mitchell, George L. Harp, and Ronald L. Johnson
Arkansas State University, Department of Biological Sciences, P. O. Box 599, State University, AR 72467; Phone (870)972-3082, fax (870)972-2638, rmitchel@navajo.astate.edu, glharp@navajo.astate.edu, rlj@navajo.astate.edu

The yellowcheek darter, Etheostoma moorei, is an endemic species found only in four headwater streams of the Little Red River, Arkansas. The purpose of the study was to determine the current population structure of Turkey, South and Middle forks. The individual streams have been isolated and largely inundated since 1962, when Greers Ferry Reservoir was created. Allozyme electrophoresis was used to determine genetic variation for 17 loci (n=86) and meristic variation was determined for six characters (n=80). The greatest divergence occurred between the Turkey Fork versus the Middle and South fork populations (Nei's unbiased genetic distance = 0.213 and 0.205, respectively). Dramatic population declines, due in part to severe drought, over the past two decades has not resulted as yet in loss of genetic diversity for populations compared to previous genetic studies (H= 0.063; P= 0.277). Meristic analysis showed less divergence than genetic analysis. ANOVA showed significant differences for three of the six meristic traits studied, whereas MANOVA showed no significant difference when the six traits were combined. The genetic distinctiveness of the Turkey Fork yellowcheek darter population warrants classification as an evolutionary significant unit and special management precautions are needed to enhance population recovery.