Intra‐ and Intersexual Selection for Multiple Traits in the Peacock (Pavo cristatus)

Abstract

Animal communication involves a multitude of signals ranging from morphological to behavioural traits. In spite of the diversity of traits used in animal signalling, most studies of sexual selection have focused on single male traits. Moreover, the two forces of sexual selection (male-male competition and female preference) may target different traits and favour the diversification of male signalling. Still, little is known on the combined effects of intra-and intersexual selection on the evolution of multiple signals. The peacock is often cited as one of the best examples of the strength of sexual selection in producing exaggerated traits. Here, we investigated traits under intra-and intersexual selection in a population of free-ranging common peafowl. Peacocks with longer trains and tarsi were more likely to establish a display territory in a central position within the lek and had a higher number of intrusions and agonistic interactions. These traits appeared therefore to be under intrasexual selection. Female selection was assessed as the number of copulations. Mating success was positively correlated with behavioural traits (display activity) and with train ornamentation (number and density of ocelli) suggesting that females use multiple cues during mate selection. Therefore, intraand intersexual selection seem to operate on different sets of traits. Overall, our results stress the role of multiple receivers on the evolution of multiple signals.

Selective attention in peacocks during assessment of rival males

“…Interestingly, previous work found that train and tarsi length in peacocks were important traits during intrasexual selection. Males with longer trains and tarsi established territories in central locations within leks and engaged in more agonistic behaviors with other males (Loyau et al, 2005). Given that peacocks were gazing along the bottom portions of their rivals' displays and their rivals' legs, they could have been assessing the width of the trains (which is positively correlated with the length of the train) and length of the tarsi.…”

“…Males compete with each other by displaying their erect trains or walking parallel to other males. If aggression escalates, they chase each other and engage in fights that consist of them jumping and using their spurs (Petrie et al, 1991;Loyau et al, 2005). Males with longer trains and tarsi establish territories in central locations within leks and engage in more agonistic behaviors with other males.…”

“…Males with longer trains and tarsi establish territories in central locations within leks and engage in more agonistic behaviors with other males. In contrast, males with shorter trains are less likely to establish display territories (Loyau et al, 2005). We monitored the gaze of freely moving peacocks as they evaluated the displays of other males to determine how they allocate their attention during rival assessment and whether their attention was influenced by the behavior of their rivals.…”

Mounting an immune response correlates with decreased androgen levels in male peafowl, Pavo cristatus

“…We choose to study these relationships in the peafowl because this species has a polygynous mating system in which high male mating success is correlated with the exaggerated display of their long trains, which are conspicuously decorated with many colourful eye-spots (Petrie et al 1991;Yasmin and Yahya 1996;Loyau et al 2005b). Møller and Petrie (2002) showed that train length correlates negatively with antibody responses to SRBC and the relative number of lymphocytes in the blood (heterophil-lymphocyte ratio).…”

The effect of claw size and wave rate on female choice in a fiddler crab

“…For example, female choice in birds has been shown to act on at least three different male traits in a single species: plumage ornamentation, courtship display and advertisement song (e.g. Borgia 1985;Marchettii 1998;Patricelli et al 2003;Coleman et al 2004;Loyau et al 2005;Patricelli et al 2006). Selection on male secondary sexual characteristics is often strongly driven by female mating preferences (Andersson 1994;Candolin 2003).…”