ABSTRACT

Some endangered species have declined to very low numbers and a few populations. Particularly in these situations, genetic information is often critical for evaluation of the existing animals and for future management. Three examples are discussed here, winter-run chinook salmon and bonytail chub, both of which exist in only one natural population, and Mexican wolves, which have been extinct in the wild and have only recently been released into eastern Arizona. A supplementation programme for winter-run chinook salmon has been ongoing since the early 1990s. Using data from n microsatellite loci, it appears that returns from these hatchery-reared fish are consistent with random expectations over both female and male parents. The potential broodstock to use for captive rearing of bonytail chub is evaluated. However, the extent of genetic variation in the potential broodstock appears very limited and is descended from between 3.5 and 8.5 effective founders as determined from allozyme data and supported by mtDNA haplotype sequence information. As a result, it is critical to incorporate the contributions from other wild-caught individuals into the broodstock. Finally, there have been concerns that Mexican wolves are not well differentiated from northern gray wolves and may have some ancestry from either coyotes or dogs. Using 20 microsatellite loci, all three lineages of Mexican wolves cluster together, are different from other canid taxa, and do not show any ancestry from either coyotes or dogs.

INTRODUCTION

Although efforts to perceive and integrate the factors that influence the numbers and persistence of rare species are not just recent, conservation biology as a comprehensive approach to understanding problems in threatened and endangered species is only a few decades old.