Sexual selection: competition for resources provided by mating partners

Ever since Darwin’s pioneering work, the definition of sexual selection has been subject to recurrent controversies. The main focus of a more recent debate centers on whether or not sexual selection encompasses intra-sexual competition for resources other than gametes. Specifically, it has been proposed to define sexual selection as competition for access to gametes and to consider competition for any other resources provided by mates as forms of natural selection. In this review, I elaborate on several drawbacks of this gamete-centered approach arguing that it (1) implies an artificial split of pre-copulatory competition for mates into two indistinguishable processes, (2) hinders the identification and quantification of sexual selection and, therefore, its distinction from other forms of natural selection, (3) gives rise to an overly male-biased perception on sexual selection, and (4) does not conform to Darwin’s original conception. In an attempt to provide a definition, which is explicit regarding the ultimate target of intra-sexual competition, I propose to define sexual selection as competition for access to reproductive resources provided by potential mating partners. I specify the main characteristics of this alternative definition in the context of previous ones and discuss potential limitations.