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Abstract Detail


Ecological Section

Archetti, Marco [1].

Evidence for the maintenance of autumn colours by coevolution.

The adaptive value of autumn colours is still a puzzle for evolutionary biology. It has been suggested that autumn colours are a warning signal towards insect pests that use the trees as a host. I explain how insect colour vision can lead to a preference for green versus red in spite of the lack of a red photoreceptor and I show that red leaves are indeed much less attractive than green leaves to insects migrating to trees with autumn colours. I also show that insect fitness in spring is lower on trees with red leaves in autumn, which suggests that red is a honest signal of quality. Moreover autumn colours are common in wild populations but not among cultivated apple varieties, which are no longer under natural selection against parasites: red leaves remain only in the varieties that are very susceptible to the effects of a common insect-borne disease, fire blight, and therefore are more in need of avoiding insects. Varieties with red leaves have also smaller fruits, which shows that they have been under less effective artificial selection. This suggests a possible trade-off between fruit size, leaf colour and resistance to parasites. These results are consistent with the hypothesis that autumn colours are a warning signal to insects, but not with other hypotheses for the evolution of autumn leaf colours. Comparative evidence also suggests that autumn colours have been acquired and lost many times during evolution and that their occurrence is correlated with the presence of parasites.


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1 - University of Oxford, St Johns College, Oxford, OX1 3JP, UK

Keywords:
coevolution
autumn colours.

Presentation Type: Oral Paper:Papers for BSA Sections
Session: 49
Location: Alpine B/Snowbird Center
Date: Tuesday, July 28th, 2009
Time: 2:15 PM
Number: 49004
Abstract ID:222


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