The role of evolution in mating behavior of lekking species  (Page 9/11)

The kin selection hypothesis

This chapter will conclude with a brief analysis of the support and opposition for kin selection as a mechanism of lek creation and persistence. Although kin selection is not a distinct hypothesis in itself, it can play a role in any of the mechanisms proposed to explain lek behavior. Kin selection is a common evolutionary explanation for the basis of many animal behaviors. At heart, the theory proposes relatedness as an explanation for behaviors that would otherwise prove disadvantageous for an organism. An organism can pass on its genes directly, through traditional reproduction, or indirectly, by increasing the reproductive fitness of its relatives who share its genes (Hamilton 1964). Thus, it is oftentimes more advantageous for an organism to forgo reproduction in order to assist in the reproductive efforts of his kin. Researchers see potential for the explanation of the group mating structure of leks in terms of kin selection and increased relatedness between members. One of the biggest conundrums of the lek system comes from trying to understand the role of lesser males on the lek. Numerous studies have shown a positive correlation between lek size and frequency of female visits to the lek (see The Preference Hypothesis), which indicates that these lesser, unsuccessful, males are actually increasing the fitness of their more successful counterparts (Petrie 1999). When considering full benefit to the organism, including indirect benefits, this behavior can be understood if the successful males are closely related to the unsuccessful males. Because lower ranking are very unlikely to successfully copulate, theoretical evidence predicts that they join leks where the dominant male is closely related so that they receive indirect benefits (Loiselle 2006).

Support

Peacocks

Peacocks establish their permanent display areas in the lek during their fourth year and return to this site every year, where they remain for the duration of the mating season (Petrie 1999). Peacocks are traditional lekking organisms in that the males play no role in reproduction once copulation is complete. On lek, the males are oftentimes as close as 2.5m from one another. Peacock leks demonstrate many characteristics of any classic lekking species. The peacocks congregate in large display arenas and call together, as a group, to attract the peahens. A peahen’s arrival at the lek signals the males to stop calling and instead display their tail coverts in competitive display behavior. Like most leks, the success of the displaying males is very skewed and the majority of the peacocks receive no copulations in return for their elaborate calling and displaying.