Urban areas are characterised by the presence of sensory pollutants, such as anthropogenic noise and artificial light at night (ALAN). Animals can quickly adapt to novel environmental conditions by adjusting their behaviour, which is proximately regulated by endocrine systems. While endocrine responses to sensory pollution have been widely reported, this has not often been linked to changes in behaviour, hampering the understanding of adaptiveness of endocrine responses. Our aim was, therefore, to investigate the effects of urbanisation, specifically urban noise and light pollution, on hormone levels in male urban and forest túngara frogs (Engystomops pustulosus), a species with reported population divergence in behaviour in response to urbanisation. We quantified testosterone and corticosterone release rates in the field and in the lab before and after exposure to urban noise and/or light. We show that urban and forest frogs differ in their endocrine phenotypes under field as well as lab conditions. Moreover, in urban frogs exposure to urban noise and light led, respectively, to an increase in testosterone and decrease in corticosterone, whereas in forest frogs sensory pollutants did not elicit any endocrine response. Our results show that urbanisation, specifically noise and light pollution, can modulate hormone levels in urban and forest populations differentially. The observed endocrine responses are consistent with the observed behavioural changes in urban frogs, providing a proximate explanation for the presumably adaptive behavioural changes in response to urbanisation.

中文翻译：

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噪音和光污染会引起城市青蛙的内分泌反应，但不会引起森林青蛙的内分泌反应。

城市地区的特点是存在感官污染物，例如人为噪音和夜间人造光 (ALAN)。动物可以通过调整自己的行为来快速适应新的环境条件，这主要受到内分泌系统的调节。虽然对感官污染的内分泌反应已被广泛报道，但这通常与行为变化无关，从而妨碍了对内分泌反应适应性的理解。因此，我们的目的是调查城市化，特别是城市噪音和光污染，对雄性城市和森林青蛙（Engystomops pustulosus）激素水平的影响，据报道，该物种因城市化而在行为上存在差异。我们量化了暴露于城市噪音和/或光线之前和之后在现场和实验室中的睾酮和皮质酮释放率。我们表明，城市青蛙和森林青蛙在野外和实验室条件下的内分泌表型有所不同。此外，在城市青蛙中，暴露于城市噪音和光线分别会导致睾丸激素增加和皮质酮减少，而在森林青蛙中，感官污染物不会引起任何内分泌反应。我们的研究结果表明，城市化，特别是噪音和光污染，可以不同地调节城市和森林人口的激素水平。观察到的内分泌反应与观察到的城市青蛙的行为变化一致，为城市化带来的适应性行为变化提供了最接近的解释。