Bare-Part Color in Female Budgerigars Changes from Brown to Structural Blue following Testosterone Treatment but Is Not Strongly Masculinized
Bare-Part Color in Female Budgerigars Changes from Brown to Structural Blue following Testosterone Treatment but Is Not Strongly Masculinized
复制标题
睾丸激素治疗后，雌性虎皮鹦鹉的裸身颜色从棕色变为结构性蓝色，但并未明显男性化
作者：
Stefanie E. P. Lahaye;M. Eens;V. Darras;R. Pinxten
虽然有一些研究表明，通过实验增加雄激素类固醇睾酮水平可以影响雌性行为，但很少有研究关注外源性睾酮对雌性形态的激活作用。关于鸟类的彩色显示，几乎只研究了睾酮操纵对雌性类胡萝卜素着色的影响。其他颜色类型，如结构色（即紫外线、蓝色和紫色，由组织纳米结构中的不同光反射产生）在很大程度上仍未得到研究。本文研究了外源睾酮对雌性虎皮猴结构裸部着色的短期和长期影响。在这种鹦鹉中，裸露部分的颜色表现在喙部，雌性的喙部是棕色的，雄性的喙部是蓝色的。我们通过实验提高了睾酮治疗女性（t型女性）的血浆睾酮水平，与对照组（c型女性）相比，我们在植入后五周内每周进行一次cere分光光度测量，十周后进行一次测量。我们还通过比较实验雌性和未治疗的雄性来估计睾酮使雌性细胞核颜色男性化的程度。我们发现，从植入后第四周开始，睾酮对睾丸素颜色有显著影响。t型雌虫比c型雌虫表达的谷粒更蓝，亮度和紫外线反射率更高。然而，t -雌性的核色仍然明显低于雄性，而t -雌性的亮度和紫外线反射率值明显高于雄性。我们的定量结果表明，外源性睾酮诱导了雌性结构蓝色的表达，但并没有强烈的雄性化雌性细胞核颜色。我们提供了睾酮对结构颜色作用的几种潜在途径。
Whereas several studies have shown that experimentally increased levels of the androgenic steroid testosterone can affect female behavior, fewer studies have focused on the activational effects of exogenous testosterone on female morphology. With respect to colorful displays in birds, almost exclusively the effects of testosterone manipulation on female carotenoid-based colorations have been studied. Other color types such as structural colors (i.e. UV, blue and violet colors that result from differential light reflection in the nanostructures of the tissue) remain largely unstudied. Here, we investigated the short- and long-term effects of exogenous testosterone on the expression of structural bare-part coloration in female budgerigars, Melopsittacus undulatus. In this parrot species, bare-part coloration is expressed in the cere, a structure over the beak which is brown in females and structural blue in males. We experimentally increased plasma testosterone levels in testosterone-treated females (T-females) compared to controls (C-females) and we performed weekly spectrophotometric measurements of the cere for five weeks after implantation and one measurement after ten weeks. We also estimated the extent to which testosterone masculinized female cere color by comparing the experimental females with untreated males. We found significant effects of testosterone on cere color from week four after implantation onwards. T-females expressed significantly bluer ceres than C-females with higher values for brightness and UV reflectance. T-female cere color, however, remained significantly less blue than in males, while values for brightness and UV reflectance were significantly higher in T-females than in males. Our quantitative results show that exogenous testosterone induces the expression of structural blue color in females but does not strongly masculinize female cere coloration. We provide several potential pathways for the action of testosterone on structural color.