Warning signal brightness variation: sexual selection may work under the radar of natural selection in populations of a polytypic poison frog

Though theory predicts consistency of warning signals in aposematic species to facilitate predator learning, variation in these signals often occurs in nature. The strawberry poison frog, Dendrobates pumilio, is an exceptionally polytypic aposematic frog exhibiting variation in warning color and brightness. In the Solarte population, males and females both respond differentially to male brightness variation. Here, we demonstrate through spectrophotometry and visual modeling that variation in aposematic brightness within this population is likely visible to two putative predators (crabs, snakes) and conspecifics, but not to the presumed major predator (birds). This study thus suggests that signal brightness within D. pumilio populations can be shaped by sexual selection, with limited opportunity for natural selection to influence this trait due to predator sensory constraints. As changes in signal brightness can ultimately lead to changes in hue, our findings at the within-population lev...

理论预测，警戒物种（aposematic species）的警戒信号应具有一致性以促进捕食者学习，但此类信号在自然界中常存在变异。草莓箭毒蛙（Dendrobates pumilio）是一种多型性极强的警戒物种，其警戒色与亮度存在显著变异。在Solarte种群中，雌雄个体均对雄性亮度变异表现出差异化响应。本研究通过分光光度法（spectrophotometry）与视觉建模证实，该种群内警戒亮度的变异可能被两种潜在捕食者（螃蟹、蛇类）及同种个体（conspecifics）感知到，但推测的主要捕食者（鸟类）无法察觉。因此，本研究表明，D. pumilio种群内的信号亮度可由性选择（sexual selection）塑造；由于捕食者的感官限制，自然选择（natural selection）对该性状的影响机会有限。由于信号亮度的变化最终可能导致色调改变，我们在种群内水平上的发现...