Relationship of Gonadal Recrudescence and Testicular Melanogenesis in California Quail

Anthony, Robert G.; Buss, Irven O.

doi:10.2307/1365818

Cited by 4 publications

(7 citation statements)

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Section: Discussionmentioning

confidence: 99%

“…Some authors have suggested that testicular melanogenesis in birds does not take place during the period of spermatogenesis (Anthony & Buss, 1974; Lake, 1981; Agrawal & Bansal, 1983; Hore et al. , 1994; and see references in Anthony & Buss, 1974 for exceptions). Our more extensive study cannot confirm that pattern, as we did not only observe testicular melanization during both breeding and nonbreeding periods, but even detected a higher probability of occurrence during the period of reproductive activity (i.e.…”

Section: Discussionmentioning

confidence: 99%

“…), we considered that they contained melanin when their colour was black or grey (see Appendix S1). Previous authors have determined that the presence of these colours in the testes of birds is because of melanin granules (Anthony & Buss, 1974; Aire, 1979; López & Paramio, 1980; Lake, 1981; Agrawal & Bansal, 1983; Hore et al. , 1994).…”

Section: Methodsmentioning

confidence: 99%

“…As some authors have suggested that testicular melanization is associated with the gonadal cycle of birds (Anthony & Buss, 1974; Lake, 1981; Agrawal & Bansal, 1983; Hore et al. , 1994; see however references in Anthony & Buss, 1974 for exceptions), we determined whether prevalence of testicular melanization was correlated between breeding and nonbreeding seasons in 20 species for which two or more adult males (range: 2–38 specimens) were examined in both periods. In these species, prevalence of testicular melanization in both periods was strongly positively correlated (Kendall tau = 0.68, P < 0.0001).…”

Section: Methodsmentioning

confidence: 99%

“…In birds, testicular melanin has been found in the interstitium, wall of seminiferous tubules, tunica albuginea and epididymis (Anthony & Buss, 1974; Aire, 1979; López & Paramio, 1980; Agrawal & Bansal, 1983). The occurrence of bird testicular melanin has been suggested to be associated with the gonadal cycle, melanogenesis being absent during the period of spermatogenic activity and appearing during the regression period (Anthony & Buss, 1974; Lake, 1981; Agrawal & Bansal, 1983; Hore et al. , 1994).…”

Section: Introductionmentioning

confidence: 99%

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Testicular melanization has evolved in birds with high mtDNA mutation rates

Galván

Møller

Erritzøe³

2011

J of Evolutionary Biology

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Melanin is mainly found in the integument of animals, but it also appears in several extracutaneous tissues. The presence of melanin in testes has been anecdotally reported in all vertebrate groups, but the causes and functions of this melanin remain unknown. Similar to other extracutaneous melanins, testicular melanin may protect male germ cells from oxidative stress. Given the high respiratory activity of spermatozoa, oxidative stress generated by mitochondrial dysfunction as a consequence of mtDNA mutations directly affects sperm viability. Thus, natural selection may favour testicular melanization in males of species with high historical mutation rates in the mitochondrial genome. Here, we tested this hypothesis using information on occurrence of testicular melanization and mutation accumulation as reflected by cytochrome b mtDNA base pair substitution rates in a large set of 134 species of birds, controlling for the confounding effects of body mass, reproductive activity and phylogeny. We found that testicular melanization has evolved in species with high rates of accumulated mitochondrial mutations and propose that this is an adaptive response related to the protective capacity of melanin against oxidative stress. In support of this hypothesis, testicular melanization was more frequently observed during the breeding season of birds (i.e. when spermatogenesis is likely to occur) than during reproductive inactivity. In contrast to other extracutaneous melanins whose abundance seems to reflect skin and coat colour, we did not find a correlation between the proportion of plumage coloured by melanins and occurrence of testicular melanization. Whereas future experimental studies should test these hypotheses, our study highlights for the first time that melanization patterns in animals may evolve as a response to historical mutation rates.

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Section: Discussionmentioning

confidence: 99%