Diversity in warning coloration is easily recognised by avian predators
Journal of Evolutionary Biology
Wiley / European Society for Evolutionary Biology (ESEB)
© 2017 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited: https://creativecommons.org/licenses/by/4.0/
Warning coloration is a widespread strategy to alert predators about prey unprofitability. The success of this strategy partly depends on predators being able to learn and recognise certain signals as indicators of toxicity, and theory predicts that this is easier if signals converge on similar colours. However, the diversity in warning signal form is astonishing, contradicting predictions. Here, we quantified ladybird signal diversity with respect to avian vision, measuring how unique and discernable each signal is from one another. In addition, we measured signal conspicuousness against a series of backgrounds, namely an average green, average brown, and where we collected each species, to determine if signals are more contrasting against the ladybirds’ local substrates than compared to average ones. This allowed us to determine if there are local adaptations in conspicuousness that promote signal diversity. We found that while ladybird signals are unique and recognisable, specialist species are more contrasting against the background they are most commonly found on. However, overall our study suggests that warning signals have evolved to be effective against a wide range of natural backgrounds, partly explaining the success of this strategy in nature.
We would like to thank V. Crawford, J. Troscianko, E. Briolat, S. Mynott, S. Smithers, J. Easley, G. McIvor, I. Medina, and two anonymous referees for their valuable comments and discussions on this work. Authors were funded by the University of Cambridge, Colciencias – Colombia, and a Biotechnology and Biological Sciences Research Council (BBSRC) David Phillips Research Fellowship (BB/G022887/1). All the authors of this work declare no conflict of interest.
This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.
Vol. 30 (7), pp. 1288-1302