Testing the sexy son hypothesis—a research framework for empirical approaches

Extract

Sexual selection by direct and/or indirect benefits as well as sexual conflict determines the evolution of animal mating systems (e.g., Andersson and Simmons 2006). In polygynous mating systems, the female preference of apparently useless or deleterious male characteristics can be understood if a correlation between preferred male characteristics and direct benefits for the female exists (see polygyny threshold model, e.g., Orians 1969), such as improved paternal care or territorial quality (e.g., Price et al. 1993; Iwasa and Pomiankowski 1999). This issue is particularly interesting in facultative polygynous mating systems with biparental care because the female's choice of a polygynous male as a mate is most often accompanied by a reduction in paternal care by this mate (for a review, see Ligon 1999). Several studies (e.g., Johnson et al. 1994; Pribil and Searcy 2001; Moreno et al. 2002; but see Both 2002) have observed a reduction in offspring number and/or offspring performance in females mated with a polygynous male, thus raising doubt in the relevancy of the polygyny threshold model (see, e.g., Orians 1969) in these instances. More generally, females of most species do not seem to take any appreciable direct benefits of their mate choice (Kirkpatrick and Ryan 1991; Andersson 1994).