Dietary niche variation and its relationship to lizard population density

Maria Novosolov*, Gordon H. Rodda, Alison M. Gainsbury, Shai Meiri

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


Insular species are predicted to broaden their niches, in response to having fewer competitors. They can thus exploit a greater proportion of the resource spectrum. In turn, broader niches are hypothesized to facilitate (or be a consequence of) increased population densities. We tested whether insular lizards have broader dietary niches than mainland species, how it relates to competitor and predator richness, and the nature of the relationship between population density and dietary niche breadth. We collected population density and dietary niche breadth data for 36 insular and 59 mainland lizard species, and estimated competitor and predator richness at the localities where diet data were collected. We estimated dietary niche shift by comparing island species to their mainland relatives. We controlled for phylogenetic relatedness, body mass and the size of the plots over which densities were estimated. We found that island and mainland species had similar niche breadths. Dietary niche breadth was unrelated to competitor and predator richness, on both islands and the mainland. Population density was unrelated to dietary niche breadth across island and mainland populations. Our results indicate that dietary generalism is not an effective way of increasing population density nor is it result of lower competitive pressure. A lower variety of resources on islands may prevent insular animals from increasing their niche breadths even in the face of few competitors.

Original languageEnglish
Pages (from-to)285-292
Number of pages8
JournalJournal of Animal Ecology
Issue number1
StatePublished - Jan 2018


FundersFunder number
Clore Israel Foundation


    • diet
    • lizards
    • niche breadth
    • niche variation hypothesis
    • population density


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