Ryan M J, Fox J H, Wilczynski W, Rand A S
Department of Zoology, University of Texas, Austin 78712.
Nature. 1990 Jan 4;343(6253):66-7. doi: 10.1038/343066a0.
The sensory bases of species and population mate preferences are well known; in frogs properties of the female auditory system influence such preferences. By contrast, there is little understanding of how sensory characteristics could result in sexual selection within a population. One possible mechanism is that females are more sensitive to male courtship signals that deviate from the population mean. We document this mechanism in the frog Physalaemus pustulosus. Female basilar papilla tuning is biased toward lower-than-average frequencies in the 'chuck' portion of the male's call, explaining female preference for the lower-frequency chucks produced by larger males. The tuning does not differ between P. pustulosus and its close relative P. coloradorum, a species in which males never evolved the ability to produce chucks; thus the female tuning evolved before the chuck and therefore the chuck played no role in the evolution of the preference. This allows us to reject two popular hypotheses for the evolution of this female preference (runaway sexual selection and natural selection) in favour of a third: sexual selection for sensory exploitation.
物种和种群配偶偏好的感官基础已为人熟知；在蛙类中，雌性听觉系统的特性会影响此类偏好。相比之下，对于感官特征如何导致种群内部的性选择，人们了解甚少。一种可能的机制是，雌性对偏离种群均值的雄性求偶信号更为敏感。我们在泡蟾属（Physalaemus）的脓疱泡蟾（Physalaemus pustulosus）中记录了这一机制。雌性基底乳头的调谐偏向于雄性叫声“咯咯声”部分低于平均频率的频率，这解释了雌性对较大雄性发出的低频咯咯声的偏好。脓疱泡蟾与其近缘种科罗拉多泡蟾（Physalaemus coloradorum）之间的调谐并无差异，而在科罗拉多泡蟾中，雄性从未进化出发出咯咯声的能力；因此，雌性的调谐在咯咯声出现之前就已进化，所以咯咯声在这种偏好的进化过程中并未发挥作用。这使我们能够摒弃关于这种雌性偏好进化的两种流行假说（失控性选择和自然选择），而支持第三种假说：感官利用的性选择。
