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

Runemark, Anna LU ; Sagonas, Kostas and Svensson, Erik LU (2015) In Ecology 96(8). p.2077-2092
Abstract
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... (More)
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. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
bite force, body shape, diet, Greece, insularity, island biogeography, island gigantism, Lacertidae, Podarcis gaigeae, population divergence, predation, Skyros wall lizard
in
Ecology
volume
96
issue
8
pages
2077 - 2092
publisher
Ecological Society of America
external identifiers
  • wos:000358454500007
  • scopus:84939223544
ISSN
0012-9658
DOI
10.1890/14-1996.1.sm
language
English
LU publication?
yes
id
264186ea-3fc7-479f-ae30-ddde764ac4b1 (old id 7767741)
date added to LUP
2015-09-09 14:34:47
date last changed
2017-04-09 03:58:39
@article{264186ea-3fc7-479f-ae30-ddde764ac4b1,
  abstract     = {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.},
  author       = {Runemark, Anna and Sagonas, Kostas and Svensson, Erik},
  issn         = {0012-9658},
  keyword      = {bite force,body shape,diet,Greece,insularity,island biogeography,island gigantism,Lacertidae,Podarcis gaigeae,population divergence,predation,Skyros wall lizard},
  language     = {eng},
  number       = {8},
  pages        = {2077--2092},
  publisher    = {Ecological Society of America},
  series       = {Ecology},
  title        = {Ecological explanations to island gigantism: dietary niche divergence, predation, and size in an endemic lizard},
  url          = {http://dx.doi.org/10.1890/14-1996.1.sm},
  volume       = {96},
  year         = {2015},
}