School of Biological Sciences, Washington State University, Pullman, WA, USA; Cornell Lab of Ornithology, Ithaca, NY, USA; Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA.
Department of Biomolecular Engineering, University of California, Santa Cruz, CA, USA; Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, USA.
Horm Behav. 2023 Aug;154:105393. doi: 10.1016/j.yhbeh.2023.105393. Epub 2023 Jun 16.
Historic bias toward study of sex hormones and sexual ornamentation in males currently constrains our perspective of hormone-behavior-phenotype relationships. Resolving how ornamented female phenotypes evolve is particularly important for understanding the diversity of social signals across taxa. Studies of both males and females in taxa with variable female phenotypes are needed to establish whether sexes share mechanisms underlying expression of signaling phenotypes and behavior. White-shouldered Fairywren (Malurus alboscapulatus) subspecies vary in female ornamentation, baseline circulating androgens, and response to territorial intrusion. The moretoni ornamented female subspecies is characterized by higher female, but lower male baseline androgens, and a stronger pair territorial response relative to pairs from the lorentzi unornamented female subspecies. Here we address whether subspecific differences in female ornamentation, baseline androgens, and pair territoriality are associated with ability to elevate androgens following gonadotropin releasing hormone (GnRH) challenge and in response to simulated territorial intrusion. We find that subspecies do not differ in their capacity to produce androgens in either sex following GnRH or simulated territorial intrusion (STI) challenges. STI-induced androgens were predictive of degree of response to territorial intrusions in females only, but the direction of the effect was mixed. GnRH-induced androgens did not correlate with response to simulated intruders, nor did females sampled during intrusion elevate androgens relative to flushed controls, suggesting that increased androgens are not necessary for the expression of territorial defense behaviors. Collectively, our results suggest that capacity to produce androgens does not underlie subspecific patterns of female ornamentation, territoriality, and baseline plasma androgens.
历史上对雄性性激素和性装饰物的研究偏向，目前限制了我们对激素-行为-表型关系的看法。解决有装饰物的雌性表型如何进化的问题，对于理解跨类群的社会信号多样性尤为重要。需要对具有可变雌性表型的雄性和雌性进行研究，以确定表达信号表型和行为的机制是否在两性中共享。白肩仙鹟（Malurus alboscapulatus）亚种在雌性装饰物、基础循环雄激素和对领地入侵的反应方面存在差异。更顿尼装饰性雌性亚种的特征是雌性基础雄激素水平较高，而雄性基础雄激素水平较低，与无装饰性洛伦茨雌性亚种的雄性相比，对配对的领地反应更强。在这里，我们探讨了雌性装饰物、基础雄激素和配对领地性的亚种差异是否与以下能力相关：在促性腺激素释放激素（GnRH）挑战后和模拟领地入侵时升高雄激素的能力。我们发现，亚种在 GnRH 或模拟领地入侵（STI）挑战后，雄性和雌性产生雄激素的能力没有差异。STI 诱导的雄激素仅预测雌性对领地入侵的反应程度，但影响的方向是混合的。GnRH 诱导的雄激素与对模拟入侵者的反应无关，也与在入侵期间采样的雌性与冲洗对照相比没有升高雄激素，这表明增加的雄激素对于表达领地防御行为不是必需的。总的来说，我们的结果表明，产生雄激素的能力不是雌性装饰物、领地性和基础血浆雄激素的亚种模式的基础。
