Data from: Evolutionary patterns of adaptive acrobatics and physical performance predict expression profiles of androgen receptor – but not oestrogen receptor – in the forelimb musculature

1. Superior physical competence is vital to the adaptive behavioural routines of many animals, particularly those that engage in elaborate sociosexual displays. How such traits evolve across species remains unclear. 2. Recent work suggests that activation of sex steroid receptors in neuromuscular systems is necessary for the fine motor skills needed to execute physically elaborate displays. Thus, using passerine birds as models, we test whether interspecific variation in display complexity predicts species differences in the abundance of androgen and oestrogen receptors (AR and ER-α) expressed in the forelimb musculature and spinal cord. 3. We find that small-scale evolutionary patterns in physical display complexity positively predict expression of AR in the main muscles that lift and retract the wings. No such relationship is detected in the spinal cord, and we do not find a correlation between display behaviour and neuromuscular expression of ER-α. Also, we find that AR expression levels in different androgen targets throughout the body – namely the wing muscles, spinal cord and testes – are not necessarily correlated, providing evidence that evolutionary forces drive AR expression in a tissue-specific manner. 4. These results suggest co-evolution between the physical prowess necessary for display performance and levels of AR expression in avian forelimb muscles. Moreover, this relationship appears to be both specific to muscle and AR-mediated signalling. 5. Given that prior work suggests that activation of muscular AR is a necessary component of physical display performance, our current data support the hypothesis that sexual selection shapes levels of AR expressed in the forelimb skeletal muscles to help drive the evolution of adaptive motor abilities.1. 优越的身体机能（superior physical competence）对诸多动物的适应性行为模式至关重要，尤其是那些呈现复杂社会性性展示的类群。这类性状在不同物种间的演化机制仍不明晰。 2. 近期研究显示，神经肌肉系统中的性类固醇受体（sex steroid receptors）激活，是完成复杂身体展示所需精细运动技能的必要前提。据此，本研究以雀形目鸟类（passerine birds）为模型，检验展示复杂度的种间差异是否可预测前肢肌肉组织与脊髓中表达的雄激素受体（androgen receptor, AR）及雌激素受体α（oestrogen receptor α, ER-α）的丰度差异。 3. 研究结果表明，身体展示复杂度的微观演化模式，与调控翅膀抬升与回缩的主要肌肉中的AR表达量呈显著正相关。脊髓中未发现此类关联，同时也未检测到展示行为与ER-α的神经肌肉表达间存在相关性。此外，我们发现全身不同雄激素靶组织（即翼肌、脊髓与睾丸）的AR表达水平未必存在关联，这为演化动力以组织特异性方式调控AR表达提供了实证依据。 4. 上述结果提示，支撑展示行为所需的身体机能，与鸟类前肢肌肉中的AR表达水平存在协同演化关系。且该关联似乎仅特异性作用于肌肉组织，且由AR介导的信号通路调控。 5. 鉴于既往研究表明，肌肉AR的激活是完成身体展示行为的必要组分，本研究数据支持如下假说：性选择通过调控前肢骨骼肌的AR表达水平，进而推动适应性运动能力的演化。