School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia.
Department of Zoology, Stockholm University, Stockholm, Sweden.
Proc Biol Sci. 2020 Jun 24;287(1929):20201011. doi: 10.1098/rspb.2020.1011.
Many organisms use different antipredator strategies throughout their life, but little is known about the reasons or implications of such changes. For years, it has been suggested that selection by predators should favour uniformity in local warning signals. If this is the case, we would expect high resemblance in colour across life stages in aposematic animals where young and adults share similar morphology and habitat. In this study, we used shield bugs (Hemiptera: Pentatomoidea) to test whether colour and colour diversity evolve similarly at different life stages. Since many of these bugs are considered to be aposematic, we also combined multi-species analyses with predation experiments on the cotton harlequin bug to test whether there is evidence of selection for uniformity in colour across life stages. Overall, we show that the diversity of colours used by both life stages is comparable, but adults are more cryptic than nymphs. We also demonstrate that nymphs and adults of the same species do not tend to look alike. Experiments on our model system suggest that predators can generalise among life stages that look different, and exhibit strong neophobia. Altogether, our results show no evidence of selection favouring colour similarity between adults and nymphs in this speciose clade.
许多生物在其一生中使用不同的防御策略，但对于这些变化的原因或影响知之甚少。多年来，人们一直认为捕食者的选择应该有利于局部警告信号的一致性。如果是这样，我们预计在具有警戒色的动物中，幼体和成年体具有相似的形态和栖息地，其颜色在各生命阶段应该高度相似。在这项研究中，我们使用盾蝽（半翅目：Pentatomoidea）来测试颜色和颜色多样性是否在不同的生命阶段以相似的方式进化。由于许多这些昆虫被认为具有警戒色，我们还将多物种分析与对棉花斑衣蜡蝉的捕食实验相结合，以测试在各生命阶段颜色是否存在选择一致性的证据。总的来说，我们表明两个生命阶段使用的颜色多样性是可比的，但成虫比若虫更具隐蔽性。我们还证明了同一物种的若虫和成虫通常看起来不一样。对我们的模型系统的实验表明，捕食者可以在外观不同的生命阶段之间进行概括，并表现出强烈的新物恐惧。总的来说，我们的结果表明，在这个多样化的进化枝中，没有证据表明选择有利于成虫和若虫之间的颜色相似性。
