Evolutionary constraints of warning signals: A genetic trade-off between the efficacy of larval and adult warning coloration can maintain variation in signal expression

Abstract

Evolutionary constraints of warning signals : a genetic trade-off between the efficacy of larval and adult warning coloration can maintain variation in signal expression. Evolution, 70 (11), 2562Evolution, 70 (11), -2572Evolution, 70 (11), . doi:10.1111 Final DraftThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/evo.13066. This article is protected by copyright. All rights reserved.

Appearance before performance? Nutritional constraints on life‐history traits, but not warning signal expression in aposematic moths

“…However, this is not perhaps so surprising as warning signal expression can be expected to be quite robust to variation in growth condition as it ensures effective protection against predators. Our results here, together with those of earlier studies, are in accordance with this expectation: the size and colour of the bright signal pattern are strongly inherited in A. plantaginis (Lindstedt et al, ; Nokelainen et al, ) and show very little environmental plasticity (Lindstedt et al, ; Lindstedt, Talsma, et al, ; Nokelainen et al, ). Thus, the role of diet‐induced plasticity in the maintenance of colour variation is likely to play a minor role compared with variation in strength and direction of selection pressures on different signal genotypes (Hegna et al, ; Lindstedt et al, ; Nokelainen et al, ).…”

“…More generally, our results suggest that availability of proteins in the diet does not constrain signal efficacy (i.e. larger and more salient pattern sizes), but it can slow down selective responses on increased melanism (Lindstedt et al, ; Ojala et al, , ). This can happen directly by constraining the melanism in forewings or indirectly via higher life‐history costs of producing melanic pattern under a low protein diet.…”

“…Our previous research has shown that production of melanic coloration in the larval stage is more costly as higher amounts of black coloration in the larval stage are negatively genetically correlated with development time in A. plantaginis (Lindstedt et al, ). Our results here are in accordance with this finding as development time was longest for individuals who originated from the small warning signal line and were reared under low protein diet (Figure b).…”

“…The larvae are hairy and have moderately conspicuous coloration comprising of an orange patch on an otherwise black body. The size of this orange patch is strongly heritable (Lindstedt et al, 2016), but has previously shown to have some level of phenotypic plasticity due to dietary conditions (Ojala et al, 2007). Larvae produce the orange patch by depositing diet-derived flavonoids and traces of eumelanin in their hairs, and the black colour is based purely on eumelanin (Lindstedt, Morehouse, et al, 2010).…”

“…We experimentally tested the life-history costs of producing and maintaining warning colour pattern under low and high resource (protein content) diets with wood tiger moths Arctia plantaginis (Arctiidae) formerly Parasemia plantaginis (Rönkä, Mappes, Kaila, & Wahlberg, 2016). The wood tiger moth is an aposematic herbivorous species whose larvae and adults show extensive phenotypic and genetic variation in their warning colour pattern (Lindstedt, Lindström, & Mappes, 2009;Lindstedt et al, 2016;Nokelainen, Lindstedt, & Mappes, 2013;Ojala et al, 2007). Both larval coloration and adult coloration are based on pigments that individuals need to synthesize de novo from protein precursors and energy derived from their diet (Lindstedt, Morehouse, et al, 2010).…”