Evidence for morph-specific substrate choice in a green-brown polymorphic grasshopper. (16th December 2021)

• Record Type: Journal Article
• Authors: Heinze, Pauline; Dieker, Petra; Rowland, Hannah M; Schielzeth, Holger
• Editors: Herberstein, Marie
• Is Part Of: Behavioral ecology. Volume 33:Number 1(2022)
• Page Start: 17
• Page End: 26
• Publication Date: 2021-12-16
• Subjects: Acrididae -- background choice -- balancing selection -- color polymorphism -- Gomphocerinae -- matching habitat choice -- microhabitat choice -- Orthoptera -- visual modeling; Animal behavior -- Periodicals; Behavior evolution -- Periodicals; Ecology -- Periodicals; Psychology, Comparative -- Periodicals; 591.5
• DOI: 10.1093/beheco/arab133
• Languages: English
• ISSNs: 1045-2249

Abstract

Abstract: 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 Pseudochorthippus parallelus. 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. Abstract : Grasshoppers are highly variable in body color. But do individuals of different color variants choose different substrates to rest on? We show that they do. Furthermore, we test if potential predators are able to perceive the differences between color variants. It turns out that some do and some do not. Individual substrate choice can thus contribute to the coexistence of different color variants within the same species in the same area.