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Ecological explanations to island gigantism: dietary niche divergence, predation, and size in an endemic lizard

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Author

Summary, in English

Although rapid evolution of body size on islands has long been known, the ecological mechanisms behind this island phenomenon remain poorly understood. Diet is an important selective pressure for morphological divergence. Here we investigate if selection for novel diets has contributed to the multiple independent cases of island gigantism in the Skyros wall lizard (Podarcis gaigeae) and if diet, predation, or both factors best explain island gigantism. We combined data on body size, shape, bite force, and realized and available diets to address this. Several lines of evidence suggest that diet has contributed to the island gigantism. The larger islet lizards have relatively wider heads and higher bite performance in relation to mainland lizards than would be expected from size differences alone. The proportions of consumed and available hard prey are higher on islets than mainland localities, and lizard body size is significantly correlated with the proportion of hard prey. Furthermore, the main axis of divergence in head shape is significantly correlated with dietary divergence. Finally, a model with only diet and one including diet and predation regime explain body size divergence equally well. Our results suggest that diet is an important ecological factor behind insular body size divergence, but could be consistent with an additional role for predation.

Publishing year

2015

Language

English

Pages

2077-2092

Publication/Series

Ecology

Volume

96

Issue

8

Document type

Journal article

Publisher

Ecological Society of America

Topic

  • Evolutionary Biology

Keywords

  • bite force
  • body shape
  • diet
  • Greece
  • insularity
  • island biogeography
  • island gigantism
  • Lacertidae
  • Podarcis gaigeae
  • population divergence
  • predation
  • Skyros wall lizard

Status

Published

Research group

  • Speciation, Adaptation and Coevolution
  • Evolution and Ecology of Phenotypes in Nature

ISBN/ISSN/Other

  • ISSN: 0012-9658