Abstract

Signal divergence and sensory preferences may lead to sexual isolation and eventually promote speciation between animal populations. However, few studies have quantified the degree of chemical signal divergence and scent-mediated sexual isolation in lizard populations. Geographic and ecological variations among populations of the whiptail lizard Aspidoscelis lineattissimus suggest that there might be chemical signal divergence among these populations. Here, we used gas chromatography-mass spectrometry to characterize and compare the chemical composition of the femoral gland secretions of male whiptail lizards of four populations from a western region of Mexico and, through behavioral experiments, explored the effects of lizard scents on precopulatory behaviors and intrasexual male-male chemical recognition among populations. Our results showed that males of each population contain a divergent mixture of compounds in their femoral gland secretions. Differential chemosensory behavior indicated that male and female lizards discriminated and were more attracted to scents of lizards from their same population. Although females also seem to discriminate male scents between populations, their associated preference to territories scent-marked by males of their own population is different between regions (eastern vs western) and not between populations. We suggest that between some populations of A. lineattissimus there may be partial premating isolation mediated by chemical signals and behavioral divergence.

Significance statement

Geographic variation in sexual signals can strongly affect discrimination and recognition abilities among reproductive individuals from divergent populations, resulting in sexual isolation and speciation. Studies suggest that reproductive isolation and speciation in lizard systems may be mediated by chemical signals, male mate preferences, and male-male interactions but not by female mate preferences. Using gas chromatography-mass spectrometry techniques and behavioral experiments, we found that chemical divergence in femoral gland secretions of male Aspidoscelis lineattissimus influences behavioral discrimination among four distinct populations. Males and females recognized and responded more toward lizard scents from their own population. In addition, some female populations were able to discriminate between territories scent-marked by males from different populations. We suggest that chemical and behavioral differences between populations may influence partial premating isolation, which can be mediated by inter and intrasexual interactions.

中文翻译：

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种群之间的化学信号差异会影响鞭尾蜥蜴Aspidoscelis lineattissimus（鳞茎：t科）的行为歧视

摘要

信号差异和感觉偏好可能导致性隔离，并最终促进动物种群之间的物种形成。但是，很少有研究量化蜥蜴种群中化学信号的扩散程度和气味介导的性隔离的程度。环纹蜥蜴Aspidoscelis lineattissimus种群的地理和生态变化提示这些人群中可能存在化学信号差异。在这里，我们使用气相色谱-质谱法对来自墨西哥西部地区的四个种群的雄性尾巴蜥蜴的股腺分泌物的化学成分进行了表征和比较，并通过行为实验探索了蜥蜴气味对早熟行为和预后行为的影响。人群中的男性内部性别化学识别。我们的结果表明，每个人群的男性在股腺分泌物中均含有多种化合物。不同的化学感应行为表明，雄性和雌性蜥蜴受到歧视，并且更容易吸引来自相同种群的蜥蜴的气味。尽管女性似乎也区分了不同人群之间的男性气味，他们对自己人口中男性所闻气味的领土的偏好偏好在不同地区（东部与西部）之间有所不同，而在不同人群之间没有差异。我们建议在A. lineattissimus可能有部分过早隔离，由化学信号和行为差异介导。

重要性声明

性信号的地理变异会严重影响不同人口的生殖个体之间的歧视和识别能力，从而导致性隔离和物种形成。研究表明，蜥蜴系统中的生殖隔离和物种形成可能是由化学信号，雄性配偶和雄性间的相互作用介导的，而不是雌性配偶。利用气相色谱-质谱技术和行为实验，我们发现雄性Aspidoscelis lineattissimus的股腺分泌物中的化学差异影响四个不同人群之间的行为歧视。男性和女性对自己本国的蜥蜴气味的认识和反应更多。另外，一些女性人群能够区分来自不同人群的男性所标记的领土。我们建议人群之间的化学和行为差异可能会影响部分过早隔离，这可以通过性交和性交相互作用来介导。