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Loss of conspicuous colouration has co-evolved with decreasing body size in populations of a poison dart frog
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal Ecology.
(English)Manuscript (preprint) (Other academic)
National Category
Zoology Evolutionary Biology
Research subject
Biology with specialization in Animal Ecology
URN: urn:nbn:se:uu:diva-179390OAI: oai:DiVA.org:uu-179390DiVA: diva2:544476
Available from: 2012-08-14 Created: 2012-08-14 Last updated: 2012-09-07
In thesis
1. Aposematism, Crypsis and Population Differentiation in the Strawberry Poison Frog
Open this publication in new window or tab >>Aposematism, Crypsis and Population Differentiation in the Strawberry Poison Frog
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Evolutionary transitions between the two major predator avoidance strategies aposematism and crypsis are expected to be associated with changes in many important traits of animals. However, empirical studies on populations experiencing ongoing or recent transitions between these strategies are rare. This thesis investigates the co-evolution of traits among populations of the Strawberry poison frog D.pumilio in Bocas del Toro, Panama. I found that all investigated populations were genetically distinct but that colour and pattern did not correlate with genetic or geographic distance, which suggests that selection needs to be invoked to explain the observed variation. Based on the chromatic contrast between frog dorsal colour and the natural habitat substrates used by the frogs, the populations were defined as bright or dull coloured. I found that frogs from bright coloured populations were larger. This is expected if aposematism is enhanced by large signals while crypsis is enhanced by small size. Further, individuals from bright coloured populations had a coarser black dorsal pattern, which is expected if crypsis is impaired by a bold pattern. The importance of pattern coarseness was confirmed by an avian detection experiment showing that coarse patterned dark green prey were more easily detected than dark green prey without pattern or with fine pattern. I put forward the hypothesis that enhanced protection, gained by aposematism, may affect behaviours that influence dispersal and pairing patterns. Indeed, males from bright coloured populations displayed at more exposed sites and showed a tendency to be more explorative and aggressive. In summary, my results show that the bright and dull coloured populations most likely represent an aposematic and a cryptic strategy, respectively. Furthermore, I show that evolutionary changes between aposematism and crypsis can be associated with coevolution of both morphology and behaviour. I argue that this coevolution may increase the likelihood of both pre- and post-zygotic reproductive isolation. This is because greater phenotypic differences between populations increase the likelihood of selection against badly adapted migrants and hybrids with intermediate traits.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2012. 43 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 956
co-evolution, population divergence, natural selection, sexual selection, warning colouration, Oophaga pumilio, Dendrobates pumilio, aggression, explorative behaviour, colour patterns
National Category
Evolutionary Biology Zoology Ecology
Research subject
Biology with specialization in Animal Ecology
urn:nbn:se:uu:diva-175240 (URN)978-91-554-8432-3 (ISBN)
Public defence
2012-09-28, Zootissalen, Villavägen 9, Uppsala, 10:00 (English)
Available from: 2012-09-06 Created: 2012-06-04 Last updated: 2013-01-22

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