ABSTRACT

Intraspecific variation in colour pattern is widespread across multitudinous amphibian species. In some species, many distinct colour patterns are maintained within populations, a phenomenon referred to as exuberant colour polymorphism. The underlying causes of exuberant colour pattern polymorphism are poorly understood but are likely explained by selection, rather than neutral processes like genetic drift. Nevertheless, empirical data are needed to understand the selective drivers of this phenomenon, but such data are currently lacking for most polymorphic species. We studied frequency, spatial, and linkage dynamics of colour pattern across nine populations of the southern cricket frog (Acris gryllus) from southeastern Georgia, USA. Using 233 individuals, we combined direct field observations with examination of natural history specimens to look at colour pattern characteristics as they relate to space, time, and sex over a 30-year time frame. We found evidence of spatial and temporal variation in colour pattern across populations. We also discovered associations among colour pattern traits and between two colour pattern traits and sex. Our results suggest that the exuberant colour polymorphism of A. gryllus may involve correlations between traits and be caused by spatial and/or temporal variation in selection. However, similar studies in other species are necessary to allow us to discriminate among different drivers of colour pattern in exuberantly polymorphic frogs. Collectively, such systems offer important opportunities for understanding the evolution of colour and phenotypic diversity.

摘要

颜色模式的种内变化在众多两栖动物中广泛存在。在某些物种中，种群内保持了许多不同的颜色模式，这种现象称为旺盛的颜色多态性。旺盛的颜色模式多态性的根本原因了解甚少，但很可能是通过选择来解释的，而不是像遗传漂移这样的中性过程来解释的。尽管如此，仍需要经验数据来了解这种现象的选择性驱动因素，但是目前对于大多数多态性物种而言，尚缺乏此类数据。我们研究了南部板球蛙（Acris gryllus）的9个种群的颜色模式的频率，空间和连锁动态），来自美国乔治亚州东南部。我们使用233个人，将直接的野外观察与自然历史标本的检查相结合，以研究30年来与空间，时间和性别相关的颜色模式特征。我们发现了人口中颜色图案的时空变化的证据。我们还发现了颜色模式特征之间以及两个颜色模式特征与性别之间的关联。我们的结果表明，A。gryllus的旺盛颜色多态性可能涉及性状之间的相关性，并可能由选择中的空间和/或时间变化引起。但是，在其他物种中进行类似的研究也是必要的，以使我们能够区分出旺盛的多形青蛙的颜色模式的不同驱动因素。总的来说，这样的系统为理解颜色和表型多样性的演变提供了重要的机会。