Anthropogenic factors, including the spread of endocrine-disrupting chemicals, have been linked to alterations in the reproductive physiology, morphology, and behavior of wildlife. Few studies of endocrine disruption, however, focus on secondary sexual traits that affect mating signals, despite their importance for reproductive success. The larynx of many anurans (frogs and toads), for example, is larger in males than in females and is crucial for producing mating calls. We aim to determine if wild populations of cane toads (Rhinella marina) near sugarcane fields in Florida have demasculinized larynges when compared to populations near urban areas. We find evidence of demasculinization in both primary and secondary sexual traits in male toads living near sugarcane. Relative to body size, the laryngeal mass, vocal cord length, and dilator muscle width are all reduced in males from sugarcane regions compared to their urban counterparts. Strong correlations between primary and secondary male sexual traits indicate that demasculinization occurs in concert both within and across diverse organs, including the testes, larynx, and skin. Our results show that anurans near sugarcane fields have demasculinized reproductive systems, that this disruption extends to secondary sexual traits like the larynx, and that it is likely due to anthropogenic causes.

中文翻译：

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野生甘蔗蟾蜍喉中的非男性化因土地利用而异。

人为因素，包括破坏内分泌的化学物质的扩散，已与野生生物的生殖生理，形态和行为发生变化有关。然而，很少有关于内分泌干扰的研究关注影响交配信号的继发性特征，尽管它们对生殖成功至关重要。例如，许多无脊椎动物（青蛙和蟾蜍）的喉头在雄性中比雌性大，并且对于产生交配声至关重要。我们的目标是确定是否有野生的甘蔗蟾蜍种群（Rhinella marina与市区附近的人口相比，佛罗里达州的甘蔗田附近的喉咙呈软化状。我们发现居住在甘蔗附近的雄性蟾蜍的主要和次要性状均出现脱男性化的迹象。相对于体型，甘蔗地区的男性相比城市人群的喉部质量，声带长度和扩张肌宽度均减少。主要和次要男性性状之间的强烈相关性表明，脱男性化发生在包括睾丸，喉和皮肤在内的多种器官内和跨器官共同发生。我们的研究结果表明，甘蔗田附近的无核生物已使男性生殖系统失调，这种破坏作用扩展到了继发性特征，如喉部，这很可能是由于人为原因引起的。