Nonindependent mate choice in monogamy

Abstract

First paragraph: Individuals usually mate with opposite-sex others based on their own assessment of prospective mates' suitability (reviews in Kempenaers 2007; Roberts and Little 2008), but this assessment can also be modulated by observing decisions of others-so-called nonindependent mate choice. We have proposed the term "mate quality bias" to describe the type of nonindependent mate choice that occurs when a female biases her own evaluation of a male in accordance with his mate's quality (Vakirtzis and Roberts 2009). This type of nonindependent choice should be expected to occur in monogamous or relatively monogamous species where, due to mutual choice, there will usually exist a high correlation between a male's quality and his mate's quality (Trivers 1972; Burley 1977; Johnstone 1997). In these species, the most desirable males will tend to mate with the most desirable females and less desirable individuals will be left to mate among themselves (Burley 1983; Jones and Ratterman 2009). In principle, this selective mapping between male and female quality will not obtain in promiscuous and polygynous species, where, due to minimal male choice and high male mating skew, the top males will mate with all willing females, whereas lower quality males will achieve fewer or no mating opportunities. In these species, it is thus unlikely that an observing female will deduce reliable information about the male from the quality of his mate; rather, the frequency of partners and/or copulations may be a more useful cue. Use of such cues in mate assessment is known as mate choice copying (Pruett-Jones 1992; Dugatkin 1998).