Seasonal variations in hair pigmentation of white‐tailed deer and their relationship to sexual activity and plasma testosterone

Bubenik, George A.; Bubenik, A. B.

doi:10.1002/jez.1402350310

Cited by 20 publications

(10 citation statements)

References 23 publications

(1 reference statement)

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“…Folding and remarkable pigmentation of the scrotum of the A. australis may be related to testes thermo-regulation in the species, probably protecting the apocrine glands against lesion by ultraviolet radiation (Jablonski & Chaplin 2000). Seasonal influence on scrotum color could not be determined from present data, but some reports focus on that point (Bubenik & Bubenik 1985). Moreover, the high skin melanization offers further protection against pholate-photolysis, which is essential to spermatogenesis (Wilson & Spaziani 1976).…”

Section: Thermo-regulatory Mechanismsmentioning

confidence: 70%

Genital morphology of the male South American fur seal (Arctocephalus australis) and biological implications

et al. 2012

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Male capacity for spreading genes to a great number of descendents and to determine population dynamics depend directly on the genital organs. Morphological studies in pinnipeds are scarce and the functional meaning of some characteristics has never been discussed. We hypothesized that Arctocephalus australis (A. australis) shows morphophysiological adaptations in order to guarantee the perpetuation of the species in the unique annual mating season. Seven males, dead from natural causes, had their genital organs collected and fixed for morphological description. Some features differ from other described mammalian males and are closely related to the biology and reproductive cycle of this species, as the scrotal epidermis, absence of glandular portion in the ductus deferens and spermatogenic epithelium suggest a recrudescent testis period. The corona glandis exhibits a singular arrangement: its erectile border looks like a formation of petals and its association with the os penis gives a "lily-flower" form to this region. We propose the name margo petaliformis to this particular erectile border of the corona glandis because of its similarity to a flower corola. The male genital organs of A. australis show morphological features compatible with adaptation to environment requirements and reproductive efficiency.

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Section: Thermo-regulatory Mechanismsmentioning

confidence: 70%

Genital morphology of the male South American fur seal (Arctocephalus australis) and biological implications

et al. 2012

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“…Subsequently, many researchers manipulated testosterone levels to test whether the expression of melanin‐based colouration is testosterone‐dependent (Buchanan et al ., ). However, even if melanin‐based colouration is correlated with testosterone levels (Bubenik & Bubenik, ) and experimental administration of testosterone increases melanin‐based colouration (Fargallo et al ., ), decreases it (Ros, ) or accelerates the production of black nuptial integument (Groothuis & Meeuwissen, ; Eising, Müller & Groothuis, ), it does not necessarily prove that variations in natural concentrations of testosterone levels caused by environmental and social factors are responsible for the inter‐individual variation in colouration observed in natural conditions. Melanogenic genes may pleiotropically regulate testosterone (Ducrest et al ., ) so that artificial administration of testosterone alters melanogenesis through feedback loops, whereas an increase in testosterone levels induced by the environment or social interactions may have no effect on melanogenesis.…”

Section: Proximate Mechanisms Of the Covariation Between Melanin‐basementioning

confidence: 99%

Condition‐dependence, pleiotropy and the handicap principle of sexual selection in melanin‐based colouration

2015

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The signalling function of melanin-based colouration is debated. Sexual selection theory states that ornaments should be costly to produce, maintain, wear or display to signal quality honestly to potential mates or competitors. An increasing number of studies supports the hypothesis that the degree of melanism covaries with aspects of body condition (e.g. body mass or immunity), which has contributed to change the initial perception that melanin-based colour ornaments entail no costs. Indeed, the expression of many (but not all) melanin-based colour traits is weakly sensitive to the environment but strongly heritable suggesting that these colour traits are relatively cheap to produce and maintain, thus raising the question of how such colour traits could signal quality honestly. Here I review the production, maintenance and wearing/displaying costs that can generate a correlation between melanin-based colouration and body condition, and consider other evolutionary mechanisms that can also lead to covariation between colour and body condition. Because genes controlling melanic traits can affect numerous phenotypic traits, pleiotropy could also explain a linkage between body condition and colouration. Pleiotropy may result in differently coloured individuals signalling different aspects of quality that are maintained by frequency-dependent selection or local adaptation. Colouration may therefore not signal absolute quality to potential mates or competitors (e.g. dark males may not achieve a higher fitness than pale males); otherwise genetic variation would be rapidly depleted by directional selection. As a consequence, selection on heritable melanin-based colouration may not always be directional, but mate choice may be conditional to environmental conditions (i.e. context-dependent sexual selection). Despite the interest of evolutionary biologists in the adaptive value of melanin-based colouration, its actual role in sexual selection is still poorly understood.

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“…This result is consistent with other studies that have shown that genetically determined melanic body color is associated with variation in aggression and other behaviors. This pattern has been found in fruit flies (Takahashi 2013), other fish (Kittilsen et al 2009), reptiles (Mafli et al 2011), birds (Roulin et al 2000;Scriba et al 2014), and mammals (Bubenik & Bubenik 1985;West & Packer 2002;Graipel et al 2014). Such behavioral differences might arise from pleiotropic effects of the alleles that determine melanic color.…”

Section: Discussionmentioning

confidence: 78%

Genetic Color Morphs in the Eastern Mosquitofish Experience Different Social Environments in the Wild and Laboratory

et al. 2016

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The social environment of an animal is an especially interesting component of its environment because it can be shaped by both genetic and non‐genetic variation among social partners. Indirect genetic effects (IGEs) are those created when genetic variation in social partners contributes to variation in an individual's phenotype; a potentially common form of IGE occurs when the expression of a behavioral phenotype depends on the particular genotypic combination of interacting individuals. Although IGEs can profoundly affect individual‐ and group‐level fitness, population dynamics, and even community structure, understanding their importance is complicated by two inherent challenges: (1) identifying individuals with genetic differences in social interactions that can contribute to IGEs and (2) characterizing natural social interactions that potentially involve IGEs. As a first step toward addressing both these challenges in the same system, we investigated social interactions involving genetically distinct male color morphs in the poeciliid fish Gambusia holbrooki under natural and laboratory conditions. Previous work indicates that melanic (M) and silver (S) males differ in social behavior and in how conspecifics respond to them, suggesting the potential for IGEs. We used a combination of live and video recording of social groups in two natural populations and in the laboratory to determine the potential for IGEs to contribute to behavioral variation in this species. We found that M males had more social partners, and especially more female social partners than did S males, in nature and in the laboratory. These results suggest that both direct and indirect genetic effects have the potential to play a role in the expression and evolution of social behavior in G. holbrooki.

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Seasonal variations in hair pigmentation of white‐tailed deer and their relationship to sexual activity and plasma testosterone

Cited by 20 publications

References 23 publications

Genital morphology of the male South American fur seal (Arctocephalus australis) and biological implications

Genital morphology of the male South American fur seal (Arctocephalus australis) and biological implications

Condition‐dependence, pleiotropy and the handicap principle of sexual selection in melanin‐based colouration

Genetic Color Morphs in the Eastern Mosquitofish Experience Different Social Environments in the Wild and Laboratory

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