Can aposematic signals evolve by gradual change?

Aposematic species, which signal conspicuously of their unprofitability to predators, have puzzled evolutionary biologists for over a century,. Although conspicuousness of unpalatable prey improves avoidance learning by predators, it also involves an evolutionary paradox: with increasing detectabili...

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Bibliographic Details
Published in:Nature (London) 1999-01, Vol.397 (6716), p.249-251
Main Authors: Lindström, Leena, Alatalo, Rauno V, Mappes, Johanna, Riipi, Marianna, Vertainen, Laura
Format: Article
Language:English
Subjects:
Animal ethology
Animals
Biological and medical sciences
Color
Evolution
Fundamental and applied biological sciences. Psychology
General aspects
Humanities and Social Sciences
letter
multidisciplinary
Predation
Predators
Prey
Psychology. Psychoanalysis. Psychiatry
Science
Science (multidisciplinary)
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Summary:Aposematic species, which signal conspicuously of their unprofitability to predators, have puzzled evolutionary biologists for over a century,. Although conspicuousness of unpalatable prey improves avoidance learning by predators, it also involves an evolutionary paradox: with increasing detectability, the deviant aposematic prey would suffer high predation initially from naive predators. Here we test a neglected idea that aposematic coloration may evolve by gradual change rather than by major mutations. Weak signals did not suffer high initial predation, but predators (great tits, Parus major) did not learn to separate them from cryptic palatable prey. Furthermore, enhanced avoidance of more conspicuous signals occurred only if predators had previously encountered relatively strong signals. Thus, the gradual-change hypothesis does not provide an easy solution to the initial evolution of aposematism through predator learning. However, the possibility remains that cost-free step-wise mutations over the range of weak signals could accumulate under neutral selection to produce effective strong signals.
ISSN:0028-0836
1476-4687
DOI:10.1038/16692