Mitochondrial DNA Variation in the Endangered Colorado Pikeminnow: A Comparison among Hatchery Stocks and Historic Specimens

Abstract

The Colorado pikeminnow Ptychocheilus lucius is a federally endangered species restricted to the Colorado River. Dexter National Fish Hatchery and Technology Center, Dexter, New Mexico, maintains three separate captive stocks of the Colorado pikeminnow: 1974YC (Yampa River), 1981YC (Green–Colorado rivers), and 1991YC (Colorado River). We surveyed mitochondrial DNA diversity in these three stocks (879 base pairs [bp]; ND-4L and ND-4 genes; N = 30) and in museum specimens collected from 1890 to 1976 (450 bp; ND-4; N = 11). All individuals had the same haplotype except for a 1-bp variant detected in 2 of the 12 fish from 1981YC. The low variation is postulated to be the result of a post-Pleistocene bottleneck in the wild and small sizes of the hatchery founder populations.