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Animals
Body Constitution
Body Constitution: drug effects
Body Mass Index
Carotenoids
Carotenoids: metabolism
Cholesterol
Cholesterol: blood
Chromatography, High Pressure Liquid
Chromatography, High Pressure Liquid: methods
Columbidae
Dihydrotestosterone
Dihydrotestosterone: pharmacology
Estradiol
Estradiol: pharmacology
Female
Hormones
Hormones: blood
Hormones: pharmacology
Male
Pigmentation
Pigmentation: drug effects
Radioimmunoassay
Radioimmunoassay: methods
Random Allocation
Sex Characteristics
Sexual Behavior, Animal
Sexual Behavior, Animal: drug effects
Sexual Behavior, Animal: physiology
Steroids
Steroids: blood
Testosterone
Testosterone: pharmacology
Up-Regulation
Up-Regulation: drug effects
Abstract:
Recent studies have demonstrated that carotenoid-based traits are under the control of testosterone (T) by up-regulation of carotenoid carriers (lipoproteins) and/or tissue-specific uptake of carotenoids. T can be converted to dihydrotestosterone (DHT) and estradiol (E2), and variation in conversion rate may partly explain some contradictory findings in the literature. Moreover, most studies on the effect of T on sexual signals have focused on the male sex only, while in many species females show the same signal, albeit to a lesser extent. We studied the effects of T, DHT, and E2 treatment in male and female diamond doves Geopelia cuneata in which both sexes have an enlarged red eye ring, which is more pronounced in males. We first showed that this periorbital ring contains very high concentration of carotenoids, of which most are lutein esters. Both T and DHT were effective in enhancing hue, UV-chroma and size in both sexes, while E2 was ineffective. However, E2 dramatically increased the concentration of circulating lipoproteins. We conclude that in both sexes both color and size of the secondary sexual trait are androgen dependent. The action of androgens is independent of lipoproteins regulation. Potential mechanisms and their consequences for trade-off are discussed.
