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Does relaxed predation drive phenotypic divergence among insular populations?

  • Anna Runemark
  • Mikkel Brydegaard
  • Erik Svensson
Publishing year: 2014
Language: English
Pages: 1676-1690
Publication/Series: Journal of Evolutionary Biology
Volume: 27
Issue: 8
Document type: Journal article
Publisher: John Wiley & Sons

Abstract english

The evolution of striking phenotypes on islands is a well-known phenomenon, and there has been a long-standing debate on the patterns of body size evolution on islands. The ecological causes driving divergence in insular populations are, however, poorly understood. Reduced predator fauna is expected to lower escape propensity, increase body size and relax selection for crypsis in small-bodied, insular prey species. Here, we investigated whether escape behaviour, body size and dorsal coloration have diverged as predicted under predation release in spatially replicated islet and mainland populations of the lizard species Podarcis gaigeae. We show that islet lizards escape approaching observers at shorter distances and are larger than mainland lizards. Additionally, we found evidence for larger between-population variation in body size among the islet populations than mainland populations. Moreover, islet populations are significantly more divergent in dorsal coloration and match their respective habitats poorer than mainland lizards. These results strongly suggest that predation release on islets has driven population divergence in phenotypic and behavioural traits and that selective release has affected both trait means and variances. Relaxed predation pressure is therefore likely to be one of the major ecological factors driving body size divergence on these islands.


  • Biological Sciences


  • BECC
  • ISSN: 1420-9101
Mikkel Brygdegaard
E-mail: mikkel [dot] brydegaard [at] forbrf [dot] lth [dot] se

Associate senior lecturer

Combustion Physics

+46 46 222 76 57



Centre for Animal Movement Research
Evolutionary Ecology, Department of Biology
Ecology building S-223 62 Lund Sweden