Gross 1993, Grahn et al 1998, Wedekind 2002). Sexual selection in natural breeding systems is known to expose heritable genetic quality, through male competition and condition-dependent characters, that is targeted by female choice and increases offspring viability (Møller and Alatalo 1999). Life history decisions that are made by certain individuals, such as precocious maturity by higher quality males, will also expose heritable genetic quality that is not captured in supportive breeding programs (Gross 1996). If potential mates differ in heritable genetic quality, maximizing genetic diversity through preventing reproductive skew is unlikely to be the best conservation strategy (Wedekind 2002).

In natural breeding systems, “genetic quality” may have three components that are targets of female mate choice: good genes, compatible genes, and diverse genes. Good genes refer to the superior fitness provided to a bearer by some genes relative to others in a population. These genes may be those most appropriate for particular pathogens or parasites (e.g., Hamilton and Zuk 1982) or for producing the enzymes that best process local prey items. Female mate choice for good genes is made possible by condition-dependent traits in males, such as body size or ornamentation that is preferred by females. For example, Reynolds and Gross (1992) showed that progeny fathered by preferred males had faster growth rates and earlier age of maturity in guppies. Moller and Alatalo (1999) reviewed a wide variety of organisms and found that males with larger condition dependent characters, favored by females, increased off-spring viability by 1.5% (even at early offspring stages in relatively benign laboratory environments). Wedekind et al. (2001) showed that female mate choice reduced pathogen-related egg mortality in whitefish, increasing egg survival by 12% relative to random mating.

Compatible genes refer to superior fitness provided to a bearer by the complementation of genes at individual loci as well as across loci. For instance, the deterioration in viability from inbreeding is often due to the expression of two deleterious alleles; compatible alleles at a locus would therefore include at least one nondeleterious allele. Female avoidance of matched deleterious alleles, through the avoidance of breeding with kin, is well known (Pusey and Wolf 1996). Female mate choice for compatible genes at the MHC locus (major histocompatibility complex) is also well known (Penn and Potts 1999). Females target opposite MHC carriers, and their heterozygote progeny have superior fitness due to disease and pathogen resistance (Carrington et al 1999). Finally, coadapted gene complexes, such as coordination of diverse body parts, is compatibility across loci and may underlie the avoidance of outbreeding in females of some species (Andersson 1994).

Wedekind (2002) discusses some advantages of incorporating mate preference into conservation breeding programs with whitefish. Since in-



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