Abstract Acoustic communication in many anuran species can show the effects of both natural and sexual selection. This is reflected in the sexually dimorphic anatomy of the larynx and ear structures, as well as the allometric relationship of these morphological traits to head or body size. In this study, we examined laryngeal and ear structures of cricket frogs Acris crepitans not only as sexually dimorphic characteristics, but also as they differ across populations in environmentally different habitats. We used 2-way ANOVA to determine whether the volumetric or linear measurements of these structures differed by sex and population. Females have significantly larger body, head, and ear sizes, but significantly smaller larynges than males. Furthermore, females as well as males show larger body and head sizes, ears, and larynges in a dryer open habitat. An ANCOVA analysis shows that males, but not females, differ in laryngeal size across populations beyond the allometric changes attributable to head size alone indicating that males have a greater degree of laryngeal population variation. In contrast, our covariate analysis found that in both sexes many of the ear differences are non-significant once head size is accounted for, suggesting that most of the population-level ear variation is due to allometric effects of body size. We conclude that although both sexes show size differences in the larynx related to selection for larger body size in dry, open habitats, selection on males for larger larynx size related to the production of lower frequency calls in those habitats does not result in correlated changes in the female larynx. The results suggest that in anurans, selection for changes in body and head size affects both sexes equally, male calls and the vocal structures responsible for them can further diversify without concordant changes in females.

中文翻译：

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性别二态性是否因人口而异？蟋蟀蛙的喉部和耳朵解剖结构

摘要 许多无尾类物种的声学交流可以显示自然选择和性选择的影响。这反映在喉部和耳朵结构的两性异形解剖结构中，以及这些形态特征与头部或身体大小的异速生长关系中。在这项研究中，我们检查了蟋蟀蛙 Acris crepitans 的喉部和耳朵结构，不仅因为它们具有两性特征，而且还因为它们在不同环境栖息地的种群之间存在差异。我们使用 2-way ANOVA 来确定这些结构的体积或线性测量是否因性别和人口而异。雌性的身体、头部和耳朵尺寸明显较大，但喉部明显小于雄性。此外，雌性和雄性都显示出更大的身体和头部尺寸、耳朵、和喉咙在干燥的开放栖息地。ANCOVA 分析表明，雄性而非雌性在不同种群的喉部大小方面存在差异，超出了仅由头部大小引起的异速生长变化，表明雄性喉部种群变异程度更大。相比之下，我们的协变量分析发现，一旦考虑到头部大小，两性中的许多耳朵差异都不显着，这表明大多数人口水平的耳朵变异是由于体型的异速生长效应。我们得出的结论是，尽管两性在干燥、开阔的栖息地中选择较大的体型相关的喉部大小差异，但与在这些栖息地中产生较低频率的呼叫相关的较大喉部尺寸的雄性选择不会导致相关的变化女性喉部。