Geographic mosaic of selection by avian predators on hindwing warning colour in a polymorphic aposematic moth

Rönkä, Katja; Valkonen, Janne K.; Nokelainen, Ossi; Rojas, Bibiana; Gordon, S.; Burdfield‐Steel, Emily; Mappes, Johanna

doi:10.1111/ele.13597

Cited by 34 publications

(40 citation statements)

References 67 publications

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“…It is also important to keep in mind that not only the community structure of predators (see e.g. [65]), but also prey communities influence the outcome of avoidance learning and generalization of distasteful prey [49].…”

Section: Discussion (A) Learning and Generalization Of Signals Associated With An Effective Escaping Abilitymentioning

confidence: 99%

Hard to catch: experimental evidence supports evasive mimicry

et al. 2021

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Most research on aposematism has focused on chemically defended prey, but the signalling difficulty of capture remains poorly explored. Similar to classical Batesian and Müllerian mimicry related to distastefulness, such ‘evasive aposematism' may also lead to convergence in warning colours, known as evasive mimicry. A prime candidate group for evasive mimicry are Adelpha butterflies, which are agile insects and show remarkable colour pattern convergence. We tested the ability of naive blue tits to learn to avoid and generalize Adelpha wing patterns associated with the difficulty of capture and compared their response to that of birds that learned to associate the same wing patterns with distastefulness. Birds learned to avoid all wing patterns tested and generalized their aversion to other prey to some extent, but learning was faster with evasive prey compared to distasteful prey. Our results on generalization agree with longstanding observations of striking convergence in wing colour patterns among Adelpha species, since, in our experiments, perfect mimics of evasive and distasteful models were always protected during generalization and suffered the lowest attack rate. Moreover, generalization on evasive prey was broader compared to that on distasteful prey. Our results suggest that being hard to catch may deter predators at least as effectively as distastefulness. This study provides empirical evidence for evasive mimicry, a potentially widespread but poorly understood form of morphological convergence driven by predator selection.

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Section: Discussion (A) Learning and Generalization Of Signals Associated With An Effective Escaping Abilitymentioning

confidence: 99%

Hard to catch: experimental evidence supports evasive mimicry

et al. 2021

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“…Additional experiments are needed to determine the interactive effects of predator's generalization, larval group size, larval defensive displays, and color. To assess whether predation risk for yellow-and white-bodied larvae varies among N. lecontei populations, future research should also test for differences in the survival of white-and yellow-bodied larvae across their geographical range and across different visual backgrounds (Rojas et al 2014;Rönkä et al 2020).…”

Section: Discussionmentioning

confidence: 99%

The impact of life stage and pigment source on the evolution of novel warning signal traits

et al. 2022

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Our understanding of how novel warning color traits evolve in natural populations is largely based on studies of reproductive stages and organisms with endogenously produced pigmentation. In these systems, genetic drift is often required for novel alleles to overcome strong purifying selection stemming from frequency-dependent predation and positive assortative mating. Here, we integrate data from field surveys, predation experiments, population genomics, and phenotypic correlations to explain the origin and maintenance of geographic variation in a diet-based larval pigmentation trait in the redheaded pine sawfly (Neodiprion lecontei), a pine-feeding hymenopteran. Although our experiments confirm that N. lecontei larvae are indeed aposematic-and therefore likely to experience frequency-dependent predation-our genomic data do not support a historical demographic scenario that would have facilitated the spread of an initially deleterious allele via drift. Additionally, significantly elevated differentiation at a known color locus suggests that geographic variation in larval color is currently maintained by selection. Together, these data suggest that the novel white morph likely spread via selection. However, white body color does not enhance aposematic displays, nor is it correlated with enhanced chemical defense or immune function. Instead, the derived white-bodied morph is disproportionately abundant on a pine species with a reduced carotenoid content relative to other pine hosts, suggesting that bottom-up selection via host plants may have driven divergence among populations. Overall, our results suggest that life stage and pigment source can have a substantial impact on the evolution of novel warning signals, highlighting the need to investigate diverse aposematic taxa to develop a comprehensive understanding of color variation in nature.

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“…A geographic mosaic theory of coevolution ( Thompson 1999 ) can predict that heterogeneous predator selection may facilitate multiple prey appearances ( Rönkä et al 2020 ). With this respect, variable light conditions have been identified as a potential source of heterogeneous selection that could result in the emergence of such phenotype variation ( Rojas et al 2014 ; Tate et al 2016 ; Passarotto et al 2018 ; Kranz et al 2018 ).…”

Section: Discussionmentioning

confidence: 99%

Context-dependent coloration of prey and predator decision making in contrasting light environments

et al. 2021

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A big question in behavioral ecology is what drives diversity of color signals. One possible explanation is that environmental conditions, such as light environment, may alter visual signaling of prey, which could affect predator decision-making. Here, we tested the context-dependent predator selection on prey coloration. In the first experiment, we tested detectability of artificial visual stimuli to blue tits (Cyanistes caeruleus) by manipulating stimulus luminance and chromatic context of the background. We expected the presence of the chromatic context to facilitate faster target detection. As expected, blue tits found targets on chromatic yellow background faster than on achromatic grey background whereas in the latter, targets were found with smaller contrast differences to the background. In the second experiment, we tested the effect of two light environments on the survival of aposematic, color polymorphic wood tiger moth (Arctia plantaginis). As luminance contrast should be more detectable than chromatic contrast in low light intensities, we expected birds, if they find the moths aversive, to avoid the white morph which is more conspicuous than the yellow morph in low light (and vice versa in bright light). Alternatively, birds may attack first moths that are more detectable. We found birds to attack yellow moths first in low light conditions, whereas white moths were attacked first more frequently in bright light conditions. Our results show that light environments affect predator foraging decisions, which may facilitate context-dependent selection on visual signals and diversity of prey phenotypes in the wild.

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Geographic mosaic of selection by avian predators on hindwing warning colour in a polymorphic aposematic moth

Cited by 34 publications

References 67 publications

Hard to catch: experimental evidence supports evasive mimicry

Hard to catch: experimental evidence supports evasive mimicry

The impact of life stage and pigment source on the evolution of novel warning signal traits

Context-dependent coloration of prey and predator decision making in contrasting light environments

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