Data from: The behavioural consequences of sex reversal in dragons

Sex differences in morphology, physiology, and behaviour are caused by sex-linked genes, as well as by circulating sex-steroid levels. Thus, a shift from genotypic to environmental sex determination may create an organism that exhibits a mixture of male-like and female-like traits. We studied a lizard species (Central Bearded Dragon, Pogona vitticeps), in which the high-temperature incubation of eggs transforms genetically male individuals into functional females. Although they are reproductively female, sex-reversed dragons (individuals with ZZ genotype reversed to female phenotype) resemble genetic males rather than females in morphology (relative tail length), general behaviour (boldness and activity level), and thermoregulatory tactics. Indeed, sex-reversed ‘females’ are more male-like in some behavioural traits than are genetic males. This novel phenotype may impose strong selection on the frequency of sex reversal within natural populations, facilitating rapid shifts in sex-determining systems. A single period of high incubation temperatures (generating thermally induced sex reversal) can produce functionally female individuals with male-like (or novel) traits that enhance individual fitness, allowing the new temperature-dependent sex-determining system to rapidly replace the previous genetically based one.

形态学、生理学与行为学层面的性别差异，由性连锁基因（sex-linked genes）以及循环性类固醇水平共同介导。因此，从基因型性别决定（genotypic sex determination）向环境性别决定（environmental sex determination）的转变，可能会催生兼具雄性与雌性特征的生物体。本研究以中部鬃狮蜥（Pogona vitticeps）为研究对象，该物种在高温孵化条件下，遗传雄性个体可被转化为具有繁殖功能的雌性个体。尽管这类性逆转个体（即由ZZ基因型逆转出雌性表型的个体）在生殖功能上属于雌性，但从形态特征（相对尾长）、基础行为模式（大胆性与活动水平）以及体温调节策略（thermoregulatory tactics）来看，它们与遗传雄性的相似度远高于遗传雌性。实际上，在部分行为性状上，性逆转的"雌性"个体比遗传雄性个体更具雄性样特征。这种新颖的表型可能对自然种群中性逆转的发生频率施加强烈的选择压力，进而推动性别决定系统的快速更迭。单次高温孵化周期（可诱导热驱动的性别逆转）即可产生携带雄性样（或全新）性状的功能性雌性个体，这些性状能够提升个体适合度（individual fitness），使得新的温度依赖型性别决定系统（temperature-dependent sex-determining system）能够快速取代原有的遗传型性别决定系统。