Heinze Pauline, Dieker Petra, Rowland Hannah M, Schielzeth Holger
Population Ecology Group, Institute of Ecology and Evolution, Friedrich Schiller University Jena, Dornburger Straße, Jena, Germany.
Research Group Predators and Toxic Prey, Max Planck Institute for Chemical Ecology, Hans-Knöll-Straße, Jena, Germany.
Behav Ecol. 2021 Dec 16;33(1):17-26. doi: 10.1093/beheco/arab133. eCollection 2022 Jan-Feb.
Orthopteran insects are characterized by high variability in body coloration, in particular featuring a widespread green-brown color polymorphism. The mechanisms that contribute to the maintenance of this apparently balanced polymorphism are not yet understood. To investigate whether morph-dependent microhabitat choice might contribute to the continued coexistence of multiple morphs, we studied substrate choice in the meadow grasshopper The meadow grasshopper occurs in multiple discrete, genetically determined color morphs that range from uniform brown to uniform green. We tested whether three common morphs preferentially choose differently colored backgrounds in an experimental arena. We found that a preference for green backgrounds was most pronounced in uniform green morphs. If differential choices improve morph-specific performance in natural habitats via crypsis and/or thermoregulatory benefits, they could help to equalize fitness differences among color morphs and potentially produce frequency-dependent microhabitat competition, though difference appear too small to serve as the only explanation. We also measured the reflectance of the grasshoppers and backgrounds and used visual modeling to quantify the detectability of the different morphs to a range of potential predators. Multiple potential predators, including birds and spiders, are predicted to distinguish between morphs chromatically, while other species, possibly including grasshoppers themselves, will perceive only differences in brightness. Our study provides the first evidence that morph-specific microhabitat choice might be relevant to the maintenance of the green-brown polymorphisms in grasshoppers and shows that visual distinctness of color morphs varies between perceivers.
直翅目昆虫的特点是体色变化很大，尤其具有广泛存在的绿褐色多态性。导致这种明显平衡多态性得以维持的机制尚不清楚。为了研究形态依赖的微生境选择是否可能有助于多种形态的持续共存，我们对草地蝗虫的底物选择进行了研究。草地蝗虫存在多种离散的、由基因决定的颜色形态，范围从均匀的棕色到均匀的绿色。我们在一个实验场地测试了三种常见形态是否会优先选择不同颜色的背景。我们发现，均匀绿色形态对绿色背景的偏好最为明显。如果差异选择通过保护色和/或体温调节益处提高了自然栖息地中形态特异性的表现，它们可能有助于平衡颜色形态之间的适合度差异，并可能产生频率依赖的微生境竞争，尽管差异似乎太小，不足以作为唯一的解释。我们还测量了蝗虫和背景的反射率，并使用视觉建模来量化不同形态对一系列潜在捕食者的可探测性。预计包括鸟类和蜘蛛在内的多种潜在捕食者能够从颜色上区分不同形态，而其他物种，可能包括蝗虫本身，只会察觉到亮度上的差异。我们的研究首次证明，形态特异性的微生境选择可能与蝗虫绿褐色多态性的维持有关，并表明颜色形态的视觉差异在不同的感知者之间有所不同。
