The breeding programs widely used to supplement fisheries and conserve endangered species may be flawed. The problem is that although animals usually choose their mates in the wild, they typically do not get a choice when bred in captivity. The benefits of mate choice can include increased resistance to disease among offspring, and new work calls for incorporating mate choice into captive breeding programs.
“Circumventing mate choice is likely to have negative consequences for the genetics of a population,” says Claus Wedekind of the University of Edinburgh in the U.K. in the October issue of Conservation Biology. “Males often are not equal with respect to genetic quality and female mate choice may be taking this into account.”
Wedekind and two coauthors previously had shown that mate choice can increase the survival of young whitefish, which are bred in hatcheries. Like many fish species, during the breeding season male whitefish develop hundreds of ornamental structures called breeding tubercles all over their bodies. Although these tiny colorless tubercles may look insignificant, they are a powerful predictor of how well a male’s young will survive: 12 percent more embryos survived a bacterial epidemic (Pseudomonas fluorescens) when their fathers had larger breeding tubercles (tubercle size ranged from about 50 to 400 microns).
Currently, most breeding programs for small populations focus on preserving genetic variation by minimizing inbreeding. Wedekind argues that as a population grows, managers should also start preserving genetic quality by incorporating mate choice into the breeding program. However, increasing genetic quality is likely to reduce genetic variation, which means managers will need to work out the optimal compromise between the two goals, he says.
There are several ways to incorporate mate choice into breeding programs including allowing
ï free mate choice for monogamous species,
ï limited mate choice either by presenting selected males to a female or by using mate-preference tests such as presenting odor samples from selected males, and
ï free mate choice for large populations of nonmonogamous species.
That said, Wedekind cautions that there are cases when free mate choice should not be allowed, such as for small populations of polygamous species.
Managers should evaluate the benefits and risks of mate choice on a case by case basis. “Any supportive breeding program, and even management of small and endangered animal populations, may benefit from incorporating knowledge about the natural breeding system, mate choice, and variance in heritable viability,” says Wedekind.
Wedekind, C. 2002. Sexual selection and life-history decisions: Implications for supportive breeding and management of captive populations. Conservation Biology 16:1204-1211