7970

• UCREFRP Catalog Number: 7970
• Author: Dowling, T. E. and W. L. Minckley.
• Title: Genetic Diversity Of Razorback Sucker As Determined By Restriction Endonuclease Analysis Of Mitochondrial DNA.
• USFW Year: 1994.
• USFW - Doc Type: Bureau of Reclamation, # 0-FC-40-09530-004,
• Copyright Material: NO

spawning stocks is undetected. Unless steps are taken to reverse this trend, remaining
populations are clearly destined to disappear in the foreseeable future.
Existing hatcheries were pressed into service to assist in conservation of such
endangered fishes (Rinne et al., 1985; Johnson and Jensen, 1991). Razorback suckers were
initially transported from Lake Mohave, Arizona-Nevada, to Dexter National Fish Hatchery
and Technology Center [DNFH] in 1981 to create a broodstock intended to provide progeny
for reintroduction and research. These fishes were thus the foundation of a captive breeding
program designed as a hedge against extinction.
The goal of such breeding programs for endangered species is to maintain a taxon in
captivity with as little change as possible. Consideration of genetic features (popularion
stricture, effective population size, etc.) is therefore critical (Templeton, 1990; Echelle, 1991;
Hedrick and Miller, 1992). Loss of genetic diversity in hatchery produced stocks (typically
due to genetic drift or inbreeding) may be deleterious, potentially reducing their ability to
respond to changing environments when reintroduced. Knowledge of and attention to
geographic distribution of genetic variation also are essential, as isolated subpopulations may
possess adaptations specific to Iocal or regional conditions. Failure to preserve locally
.distinctive stocks will result in loss of their unique adaptations, reducing the evolutionary
potential of the species.
Given the importance of genetics in formulation of conservation strategies, two sets of
molecular characters (allozymes and mitochondrial DNA [mtDNA]) were used to examine
distribution of genetic variation in razorback suckers. We discuss analysis of mtDNA
variation; results from congruent aiiozyme analyses will be provided separately by
investigators from University of California, Los Angeles. Our examination of mtDNA
restriction site variation is presented in two parts: 1) variation within and among~emaining
2