Good genes, oxidative stress and condition–dependent sexual signals

Abstract

The immune and the detoxication systems of animals are characterized by allelic polymorphisms, which underlie individual di¡erences in ability to combat assaults from pathogens and toxic compounds. Previous studies have shown that females may improve o¡spring survival by selecting mates on the basis of sexual ornaments and signals that honestly reveal health. In many cases the expression of these ornaments appears to be particularly sensitive to oxidative stress. Activated immune and detoxication systems often generate oxidative stress by an extensive production of reactive metabolites and free radicals. Given that tolerance or resistance to toxic compounds and pathogens can be inherited, female choice should promote the evolution of male ornaments that reliably reveal the status of the bearers' level of oxidative stress. Hence, oxidative stress may be one important agent linking the expression of sexual ornaments to genetic variation in ¢tness-related traits, thus promoting the evolution of female mate choice and male sexual ornamentation, a controversial issue in evolutionary biology ever since Darwin.

Ultraviolet reflectance by the cere of raptors

“…They also suggest a link between UV and carotenoid-based signalling, which has implications for the honesty of the signal (von Schantz et al 1999). Our data and colour measurements were from wild raptors and made in the field, which is both valuable and a limitation.…”

“…Carotenoids are not only deposited in ornaments, they are also important antioxidants and powerful immunostimulants (Møller et al 2000). Thus, competition for the available pool of carotenoids between ornaments and immune function may confer honesty on sexual signals (von Schantz et al 1999). Recent studies have suggested links between carotenoid based coloration and plumage (structural) UV reflectance, because carotenoid spectra often exhibit a secondary reflectance peak in the near-UV wavelengths (Burkhardt 1989;Bleiweiss 2004Bleiweiss , 2005.…”

Color in competition contexts in non-human animals

“…Other hypotheses require the production of colour to involve physiological costs, such that colour signals health or condition. For example, colour may reflect dietary access to pigments (Hill, 2006), the bearer's ability to overcome a handicap (Zahavi, 1975), resist pathogens (Hamilton & Zuk, 1982), cope with the immunosuppressive effects of testosterone (Folstad & Karter, 1992) or the costs of oxidative stress (von Schantz, Bensch, Grahn, Hasselquist, & Wittzell, 1999); or the ability to withstand stressors (Buchanan, 2000;Hillgarth & Wingfield, 1997;Westneat & Birkhead, 1998). At a genetic level, colour may signal overall genetic diversity and fitness (Brown, 1997), or genetic quality related to particular coding loci, such as the major histocompatibility complex (MHC), a multigene family that plays a critical role in the immune response (Penn & Potts, 1998).…”

Mating strategy, disgust, and food neophobia

“…Immunological competence has been hypothesized to be an important marker of genetic quality, or "good genes" (Fessler et al, 2004;Hamilton & Zuk, 1982;von Schantz, Bensch, Grahn, Hasselquist, & Wittzell, 1999), which women prioritize more in short-term than long-term mating (Buss & Schmitt, 1993;Gangestad & Thornhill, 1997b;Waynforth, Delwadia, & Camm, 2005), and whose importance increases at ovulation -when women's short-term mating psychology looms largest Gangestad, Thornhill, & Garver-Apgar, 2005;Garver-Apgar, Gangestad, & Thornhill, 2008;Gildersleeve, Haselton, & Fales, 2014). Consequently, men's displays of food neophilia should be more relevant and more effective as mating advertisements in short-term than in long-term mating contexts.…”