Yellow and the Novel Aposematic Signal, Red, Protect Delias Butterflies from Predators.

Jocelyn Liang Qi Wee,Antónia Monteiro,Daniel Osorio

doi:10.1371/journal.pone.0168243

Jocelyn Liang Qi Wee, Antónia Monteiro + Show 1 more

Open Access

https://doi.org/10.1371/journal.pone.0168243

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Journal: PloS one	Publication Date: Jan 6, 2017
Citations: 13	License type: CC BY 4.0

Affiliation: National University of Singapore, Yale-NUS College

Abstract

Butterflies of the South Asian and Australian genus Delias possess striking colours on the ventral wings that are presumed to serve as warning signals to predators. However, this has not been shown empirically. Here we experimentally tested whether the colours of one member of this diverse genus, Delias hyparete, function as aposematic signals. We constructed artificial paper models with either a faithful colour representation of D. hyparete, or with all of its colours converted to grey scale. We also produced models where single colours were left intact, while others were converted to grey-scale or removed entirely. We placed all model types simultaneously in the field, attached to a live mealworm, and measured relative attack rates at three separate field sites. Faithful models of D. hyparete, suffered the least amount of attacks, followed by grey-scale models with unaltered red patches, and by grey-scale models with unaltered yellow patches. We conclude that red and yellow colours function as warning signals. By mapping dorsal and ventral colouration onto a phylogeny of Delias, we observed that yellow and red colours appear almost exclusively on the ventral wing surfaces, and that basal lineages have mostly yellow, white, and black wings, whereas derived lineages contain red colour in addition to the other colours. Red appears to be, thus, a novel adaptive trait in this lineage of butterflies.

Highlights

Noxious animals often advertise their unpalatability to predators via the use of warning signals, called aposematic signals, in the form of bright conspicuous colouration [1]
By comparing the predation of models faithfully resembling the wild-type D. hyparete (Wt) colour pattern with that of models with parts of the colour pattern replaced by a grey shade, our study tried to address which of the colours of the Painted Jezebel was producing the aposematic response
Our study has shown no significant difference in predation between Red and Yellow model types of D. hyparete, we propose that warning signal efficacy may have evolved gradually within the genus Delias, with red being a derived and slightly more effective aposematic color

Summary

Introduction

Noxious animals often advertise their unpalatability to predators via the use of warning signals, called aposematic signals, in the form of bright conspicuous colouration [1]. Naïve predators of aposematic species learn to form an association between warning colours and unpalatability through repeated exposure to the aposematic prey [10]. Aposematic colours lead to rapid recognition of distasteful prey, minimizing predators’ wasted predation attempts, and leading to increased prey survival [11]. For optimal learning of an aposematic signal, the signal should be (i) detected by potential predators, (ii) improve memory retention in the predator, and (iii) aid accurate recognition of prey so as to facilitate avoidance learning by predators [10].

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