Correlations between lizard cranial shape and diet: A quantitative, phylogenetically informed analysis

Keith A. Metzger, Anthony Herrel

Research output: Contribution to journalArticle

60 Scopus citations

Abstract

Although the relationship between dietary and phenotypic specialization has been well documented for many vertebrate groups, it has been stated that few such general trends can be established for lizards. This is often thought to be due to the lack of dietary specialization in many lizards. For example, many species that are reported to be insectivorous may also consume a variety of plant materials, and the reverse is often true as well. In this study, we investigate whether a correlation exists between general cranial form and dietary niche in lizards. Additionally, we test previously proposed hypotheses suggesting that herbivorous lizards should be larger bodied than lizards with other diets. Our data indicate that lizards specializing in food items imposing different mechanical demands on the feeding system show clear patterns of morphological specialization in their cranial morphology. True herbivores (diet of fibrous and tough foliage) are clearly distinguished from omnivorous and carnivorous lizards by having taller skulls and shorter snouts, likely related to the need for high bite forces. This allows herbivores to mechanically reduce relatively less digestible foliage. Carnivores have relatively longer snouts and retroarticular processes, which may result in more efficient capture and processing of elusive prey. When analysed in an explicit phylogenetic context, only snout length and skull mass remained significantly different between dietary groups. The small number of differences in the phylogenetic analyses is likely the result of shared evolutionary history and the relative paucity of independent origins of herbivory and omnivory in our sample. Analyses of the relationship between diet and body size show that on average herbivores have a larger body size than carnivores, with omnivores intermediate between the two other dietary groups.

Original languageEnglish (US)
Pages (from-to)433-466
Number of pages34
JournalBiological Journal of the Linnean Society
Volume86
Issue number4
DOIs
StatePublished - Dec 1 2005

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Keywords

  • Body size
  • Feeding system
  • Herbivory
  • Lepidosaur
  • Omnivory
  • Skull

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics

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