Data from: Hormonally mediated increases in sex-biased gene expression accompany the breakdown of between-sex genetic correlations in a sexually dimorphic lizard

The evolution of sexual dimorphism is predicted to occur through reductions in between-sex genetic correlations (rmf) for shared traits, but the physiological and genetic mechanisms that facilitate these reductions remain largely speculative. Here, we use a paternal half-sibling breeding design in captive brown anole lizards (Anolis sagrei) to show that the development of sexual size dimorphism is mirrored by the ontogenetic breakdown of rmf for body size and growth rate. Using transcriptome data from the liver (which integrates growth and metabolism), we show that sex-biased gene expression also increases dramatically between ontogenetic stages bracketing this breakdown of rmf. Ontogenetic increases in sex-biased expression are particularly evident for genes involved in growth, metabolism, and cell proliferation, suggesting that they contribute to both the development of sexual dimorphism and the breakdown of rmf. Mechanistically, we show that treatment of females with testosterone stimulates the expression of male-biased genes while inhibiting the expression of female-biased genes, thereby inducing male-like phenotypes at both organismal and transcriptomic levels. Collectively, our results suggest that sex-specific modifiers such as testosterone can orchestrate sex-biased gene expression to facilitate the phenotypic development of sexual dimorphism while simultaneously reducing genetic correlations that would otherwise constrain the independent evolution of the sexes.

性二态性的演化被认为是通过共享性状的性间遗传相关（rmf）的降低而发生的，但促成这些降低的生理与遗传机制在很大程度上仍处于推测阶段。本研究针对圈养棕色安乐蜥（Anolis sagrei）采用父系半同胞育种设计，结果显示，体型与生长速率的性间遗传相关（rmf）在个体发育过程中出现瓦解，这一过程与体型二态性的发育过程相呼应。通过对整合生长与代谢功能的肝脏进行转录组分析，我们发现，在性间遗传相关（rmf）发生瓦解前后的个体发育阶段，性别偏向性基因表达水平也显著升高。个体发育过程中升高的性别偏向性基因表达，尤其富集于生长、代谢与细胞增殖相关的基因，提示这些基因既参与性二态性的发育，也促成了性间遗传相关（rmf）的瓦解。从机制层面来看，对雌性个体施加睾酮处理，可激活雄性偏向基因的表达并抑制雌性偏向基因的表达，从而在个体水平与转录组水平上诱导出类雄性表型。综上，本研究结果表明，睾酮这类性别特异性调控因子可通过调控性别偏向性基因表达，促进性二态性的表型发育，同时降低性间遗传相关，解除其对两性独立演化的约束。