Female finery is not for males

Sexual Selection in Males and Females

“…Where females compete directly with each other, it is often unclear precisely what they are competing for. Where females have developed obvious secondary sexual characters, it is often uncertain whether these are used principally to attract males or in intrasexual competition for resources, and how their development is limited is unknown (33,49). And, where males show consistent mating preferences for particular categories of females, we do not yet know whether they are usually selecting for heritable differences in female quality or for nonheritable variation in fecundity or for both.…”

“…Sexual selection operating in females may reduce the degree of sexual dimorphism, in some cases leading to monomorphism. For example, in a number of birds where females and males have similar ornaments, both sexes are commonly involved in aggressive displays with rivals, indicating that intrasexual competition may be involved (32,33). In a small number of animals, the resources necessary for successful breeding in females are so heavily concentrated that reproductive competition between females is more frequent or more intense than between males, despite greater investment in parental care by females (34).…”

“…Because of their greater energetic investment in gametes and parental care, females more commonly compete with each other for access to resources necessary for successful reproduction (including breeding sites, parental care, and social rank) than for access to gametes produced by the opposite sex (33,34). As a result, the relative intensity of intrasexual competition and the development of traits that increase competitive success in females may be more strongly influenced by differences in resource distribution than by variation in mating systems.…”

“…Although male competition and the evolution of increased body size in males is commonly associated with higher juvenile mortality and reduced longevity in males compared to females (9), there is little evidence that sex differences in survival are reversed in species where reproductive competition is more intense and secondary sexual characters are more highly developed in females. One possibility is that the costs of female expenditure on competition or ornamentation depress fecundity or parental investment and that these effects constrain the development of secondary sexual characters below the level at which they have measurable costs to female survival (33). For example, where increased competitive success in females is associated with elevated testosterone levels, these may have adverse effects on the fecundity of females (63) or on the development of their offspring (64), which constrain the evolution of further increases.…”

Same trait, different receiver response: unlike females, male American goldfinches do not signal status with bill colour

“…Although the mutual selection and social selection hypotheses have gained much attention in recent years (Amundsen, 2000;CluttonBrock, 2007;, many studies have failed to find evidence that ornamentation functions as a social signal in both males and females (reviewed in Kraaijeveld, Kraaijeveld-Smit, & Komdeur, 2007). As such, there is growing acknowledgment that a complex interplay of selective processes may account for elaborate traits when expressed in both sexes (LeBas, 2006). Some research has revealed that male and female ornamental traits may function in different selective contexts; for example, an elaborate trait may have sexually or socially selected ornamental function in one sex, while in the other sex, the trait may have evolved in response to natural selection for viability (e.g.…”