Testosterone increases UV reflectance of sexually selected crown plumage in male blue tits

Roberts, M.L.; Ras, Erica

doi:10.1093/beheco/arp028

Cited by 50 publications

(51 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, our study is the first, to our knowledge, demonstrating T-regulated sexual dichromatism in a member of the Passeriformes. Many temperate zone passerines for which the mechanisms underlying dichromatic and intrasexually polychromatic plumage color patterns have been well studied acquire breeding plumage during a postnuptial molt, when gonads are regressed and androgen levels are low (Gonzalez et al, 2001;Nolan et al, 1992;Roberts et al, 2009;Stoehr and Hill, 2001). In these species, females treated with T fail to produce the male-typical coloration (Keck, 1934;Witschi, 1961) and T treatment can delay molt in both sexes (Clotfelter et al, 2004;Dawson, 1994;Kurvers et al, 2008;Nolan et al, 1992;Runfeldt and Wingfield, 1985;Stoehr and Hill, 2001).…”

Section: T-dependent Carotenoid-based But Not Eumelanin-based Dichrommentioning

confidence: 99%

“…However, this hypothesis does not take into account the facts that: T-treated female Charadriiform species do not produce all components of the male signal (indicating that other mechanisms may also function; Lank et al, 1999); female Passeriformes can naturally produce some components of the maletypical elaborate plumage (e.g. Morales et al, 2007), which argues against genetic fixation or strict hormonal activation; and variation in male Passeriform coloration can respond to T (Gonzalez et al, 2001;Lindsay et al, 2011;Peters et al, 2000;Roberts et al, 2009), even in species in which sexual dichromatism appears to be LH dependent (e.g. house sparrow, Passer domesticus; Witschi, 1961).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Testosterone activates sexual dimorphism including male-typical carotenoid but not melanin plumage pigmentation in a female bird

Lindsay

Barron

Webster

et al. 2016

Journal of Experimental Biology

View full text Add to dashboard Cite

In males it is frequently testosterone (T) that activates the expression of sexually selected morphological and behavioral displays, but the role of T in regulating similar traits in females is less clear. Here, we combine correlational data with results from T and gonadotropinreleasing hormone (GnRH) manipulations in both sexes to assess the role of T in mediating sexually dimorphic coloration and morphology in the red-backed fairy-wren (Malurus melanocephalus). We show that: (1) natural variation in female expression of ornamental traits (darkened bills and red back feathers) is positively associated with age and circulating androgen titres, (2) females have the capacity to express most male-typical traits in response to exogenous T, including carotenoid-pigmented body plumage, shorter feathers, darkened bill and enlarged cloacal protuberance, but (3) appear constrained in production of male-typical melanin-pigmented plumage, and (4) low androgen levels during the pre-nuptial molt, probably because of low ovarian capacity for steroid production (or luteinizing hormone sensitivity), prevent females from developing male-like ornamentation. Thus, females appear to retain molecular mechanisms for hormonally regulated male-typical ornamentation, although these are rarely activated because of insufficient production of the hormonal signal.

show abstract

Section: T-dependent Carotenoid-based But Not Eumelanin-based Dichrommentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Testosterone activates sexual dimorphism including male-typical carotenoid but not melanin plumage pigmentation in a female bird

Lindsay

Barron

Webster

et al. 2016

Journal of Experimental Biology

View full text Add to dashboard Cite

show abstract

“…In a follow-up experimental study, T levels were manipulated in juvenile males during the molt period and UV chroma of the crown was measured during the breeding season. Male blue tits implanted with T during molt developed crown feathers with higher UV chroma than non-manipulated males in the subsequent breeding season (Roberts et al 2009). T is thought to influence plumage coloration outside of the molt period by increasing preening behavior (Serra et al 2007;Griggio et al 2009;Roberts et al 2009).…”

Section: Introductionmentioning

confidence: 99%

Structural coloration signals condition, parental investment, and circulating hormone levels in Eastern bluebirds (Sialia sialis)

et al. 2012

View full text Add to dashboard Cite

Many of the brilliant plumage coloration displays of birds function as signals to conspecifics. One species in which the function of plumage ornaments has been assessed is the Eastern bluebird (Sialia sialis). Studies of a population breeding in Alabama (USA) have established that plumage ornaments signal quality, parental investment, and competitive ability in both sexes. Here we tested the additional hypotheses that (1) Eastern bluebird plumage ornamentation signals nest defense behavior in heterospecific competitive interactions and (2) individual variation in plumage ornamentation reflects underlying differences in circulating hormone levels. We also tested the potential for plumage ornaments to signal individual quality and parental investment in a population breeding in Oklahoma (USA). We found that Eastern bluebirds with more ornamented plumage are in better condition, initiate breeding earlier in the season, produce larger clutches, have higher circulating levels of the stress hormone corticosterone, and more ornamented males have lower circulating androgen levels. Plumage coloration was not related to nest defense behavior. Thus, plumage ornamentation may be used by both sexes to assess the physiological condition and parental investment of prospective mates. Experimental manipulations of circulating hormone levels during molt are needed to define the role of hormones in plumage ornamentation.

show abstract

“…The fact that males that were previously in the high T treatment group (and still had significantly higher T than males that had been in the control group) exhibited higher antibody responses than controls during the moult and in the spring suggests that they were more immunocompetent than C males, at least in terms of humoral immunity. In a separate study on the same experimental subjects, we found that males from the high T group had higher crown UV chroma (a sexually selected signal) in the spring than C males (Roberts et al, 2009). The combination of superior quality sexual signals as well as a robust antibody response suggest that high T during the breeding season is indicative of high quality, because only high T males can both fully express their sexual signals and maintain a fully responsive humoral immune system.…”

Section: Discussionmentioning

confidence: 71%

“…Our experimental T manipulation during moult appeared to have caused a permanent alteration in male phenotype, creating males with higher T, higher antibody responses and more UV crown colour [a sexual signal (Roberts et al, 2009)]. The birds were around nine weeks of age when they were implanted with T or control implants -much older than other avian studies that have found an organisational effect of exogenous T (Strasser and Schwabl, 2004;Eising et al, 2006), although there is evidence in mammals that T can have organisational effects during the juvenile stage of development (Abitbol et al, 1999;Eichmann and Holst, 1999;Sisk and Zehr, 2005).…”

Section: Discussionmentioning

confidence: 99%

Is testosterone immunosuppressive in a condition-dependent manner? An experimental test in blue tits

Roberts

Peters

2009

Journal of Experimental Biology

Self Cite

View full text Add to dashboard Cite

SUMMARYIn this experiment we manipulated testosterone (T) and condition in juvenile male blue tits (Cyanistes caeruleus) during the moult, to test whether T's supposed immunosuppressive qualities are condition-dependent. To achieve this, we used T and control implants in combination with a dietary manipulation. We measured responses to both phytohaemagglutinin (PHA) and humoral immune challenges during the period of the treatments (moult) and also in the following breeding season (spring). During moult, males fed the enhanced diet were in better condition but there was no difference in humoral response between the dietary groups. T males produced a greater humoral antibody response than control (C) males. In the spring, males that had been previously treated with high T again exhibited higher antibody responses than C males. High T levels during moult were associated with a low PHA response but only in males with low body mass: heavier males that had high T exhibited the highest PHA responses. In the spring, the pattern of PHA responses was reversed; responses were highest in males that had low body mass but also had high T levels, and the lowest responses were by males that had both high T and were relatively heavy. Our results suggest that the effects of T on immunity can be either immunoenhancing or immunosuppressive, depending upon the condition of the individual, its life history stage, as well as on the immune challenge employed.

show abstract

Testosterone increases UV reflectance of sexually selected crown plumage in male blue tits

Cited by 50 publications

References 51 publications

Testosterone activates sexual dimorphism including male-typical carotenoid but not melanin plumage pigmentation in a female bird

Testosterone activates sexual dimorphism including male-typical carotenoid but not melanin plumage pigmentation in a female bird

Structural coloration signals condition, parental investment, and circulating hormone levels in Eastern bluebirds (Sialia sialis)

Is testosterone immunosuppressive in a condition-dependent manner? An experimental test in blue tits

Contact Info

Product

Resources

About