Retracted: What Determines Sex Roles in Mate Searching?

Abstract

In a seminal paper, Hammerstein and Parker (1987) described how sex roles in mate searching can be frequency dependent: the need for one sex to perform mate searching is diminished when the opposite sex takes on the greater searching effort. Intriguingly, this predicts that females are just as likely to search as males, despite a higher potential reproductive rate by the latter sex. This prediction, however, is not supported by data: male mate searching prevails in nature. Counterexamples also exist in the empirical literature. Depending on the taxon studied, female mate searching can arise in either low-or high-density conditions, and suggested explanations differ accordingly. We examine these puzzling observations by building two models (with and without sperm competition). When sperm competition is explicitly included, male mate searching becomes the dominant pattern; when it is excluded, male mate searching predominates only if we assume that costs of searching are higher for females. Consequently, two hypotheses emerge from our models. The multiple-mating hypothesis explains male searching on the basis of the ubiquity of sperm competition, and predicts that female searching can arise in low-density situations in which sperm can become limiting.It can also explain cases of female pheromone production, where males pay the majority of search costs. The sex-specific cost hypothesis predicts the opposite pattern of female searching in high-density conditions, and it potentially applies to some species in which sperm limitation is unlikely.

The Mothematics of Female Pheromone Signaling: Strategies for Aging Virgins

“…Theory predicts that pheromonal communication can make the two sexes pay asymmetric costs, with females paying much less than males (Kokko and Wong 2007). It is consequently no surprise that Lepidoptera-dominated research into pheromonal communication has found it difficult to identify costs of this modality of signaling (Johansson and Jones 2007;Symonds and Elgar 2008).…”

“…In such cases, an intermediate rather than maximal signaling effort can still be selected for, if high signaling effort is costly. Such costs can be difficult to detect precisely because females are not typically expected to evolve highly costly mate acquisition traits (Kokko and Wong 2007), but it is noteworthy that (1) costs can shape mating systems even if they are small or (2) sometimes sperm limitation can make females evolve costly mate acquisition traits (for insect data, see Charlat et al 2007;Calabrese et al 2008;Rhainds 2010; for data from spatially varying situations, see Contarini et al 2009;Rhainds 2012). Accordingly, we now assume that multiple male arrivals are not costly (we modify the above model to have k ≥ 1) and include direct costs of pheromone production.…”

“…In most taxa, males perform the majority of mate searching (Barnes 1982;Kasumovic and Andrade 2004;Kasumovic et al 2007;Ambrogi et al 2008), and females are more likely than males to encounter more mates than required for optimal fitness (Kokko and Wong 2007). Encountering too many mates can be costly rather than merely superfluous (Arnqvist and Nilsson 2000;Kawagoe et al 2001).…”

“…Recent evidence suggests that pheromone producers pay both fitness and physiological costs (Foster and Johnson 2011;Harari et al 2011). The general lack of evidence for pheromone production costs may reflect methodological difficulties (studies on concentrations of released pheromone are uncommon), or the scarcity of documented cases may match the theoretical prediction that females should expend minimal energy on pheromone production (Kokko and Wong 2007).…”

Risk-sensitive mating decisions in a visually compromised environment

“…Why? Owing to their conspicuous reproductive behaviours, males, in general, tend to be more vulnerable to predators than are females (reviewed in Kokko & Wong 2007). The actual risk of being eaten, however, can vary among males.…”