The cost of producing a sexual signal: testosterone increases the susceptibility of male lizards to ectoparasitic infestation

Testosterone, ticks and travels: a test of the immunocompetence-handicap hypothesis in free-ranging male sand lizards

“…There was a direct relationship between badge size and mating success, but no relationship between testosterone levels and the size of the badge. This latter result is in agreement with our previous studies (Olsson & Silverin 1997), but di¡ers from those of two studies in which testosterone e¡ects on male nuptial coloration were con¢rmed (Cooper et al 1987;Salvador et al 1996). In our 1997 study, however, we controlled for growth rate in partial correlation analyses of the colourt estosterone-level relationship.…”

Adaptation, Exaptation, and Constraint: A Hormonal Perspective

“…The extravagance handicap is assumed for the advantages it confers in mate choice; the cost that the handicap imposes also constrains the evolution of further extravagance. Sim-S12 The American Naturalist ilar connections among hormones, sexual selection, and parasites have recently been made in other groups of organisms (e.g., Salvador et al 1996;Klein et al 1997). While the idea of a hormonal handicap has its critics (see, e.g., Owens and Short 1995; for review), it is compelling, and further work should reveal whether it is supported.…”

A permanent signal related to male pairing success and survival in the lizard Psammodromus algirus

“…Males develop head orange coloration during the breeding season, whose extension is positively associated with plasma testosterone concentration (Díaz et al, 1994). This is a costly trait (Salvador et al, 1996) that may emphasize the size of an individual's head, possibly conferring a honest signal of fighting ability (Cooper et al, 1987;Olsson, 1994). However, this badge may also signal aggressiveness and may not tightly linked to size.…”

“…Elevated levels of androgens can be energetically costly (Marler et al, 1995) and also may compromise the immune system (Salvador et al, 1996). Thus, the expression of this temporal signal seems to be linked to male condition early in the breeding season, and the information provided by it is limited.…”