Optimal foraging constrains macroecological patterns: body size and dietary niche breadth in lizards

• Published in: Global ecology and biogeography 2008-09, Vol.17 (5), p.670-677
• Main Authors: Costa, Gabriel C, Vitt, Laurie J, Pianka, Eric R, Mesquita, Daniel O, Colli, Guarino R
• Format: Article
• Language: English
• Subjects: Amphibia. Reptilia; Animal and plant ecology; Animal, plant and microbial ecology; Biogeography; Biological and medical sciences; Biological taxonomies; Body size; Diet; Ecological genetics; Ecological niches; Foraging; Fundamental and applied biological sciences. Psychology; General aspects; herbivore; Lacertilia; lizard; Lizards; macroecology; niche breadth; optimal foraging; phylogenetic contrast; Phylogenetics; predator; Predators; prey size; Synecology; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution
• ISSN: 1466-822X; 1466-8238; 1466-822X
• DOI: 10.1111/j.1466-8238.2008.00405.x

To explore and identify probable mechanisms contributing to the relationships among body size, dietary niche breadth and mean, minimum, maximum and range of prey size in predaceous lizards. Our data set includes species from tropical rainforests, semi-arid regions of Brazil, and from deserts of the south-western United States, Australia and the Kalahari of Africa. We calculated phylogenetic and non-phylogenetic regressions among predator body size, dietary breath and various prey size measures. We found a negative association between body size and dietary niche breadth in 159 lizard species sampled across most evolutionary lineages of squamate reptiles and across major continents and habitats. We also show that mean, minimum, maximum and range of prey size were positively associated with body size. Our results suggest not only that larger lizards tend to eat larger prey, but in doing so offset their use of smaller prey. Reduction of dietary niche breadth with increased body size in these lizards suggests that large predators target large and more profitable prey. Consequently, the negative association between body size and niche breadth in predators most likely results from optimal foraging. Though this result may appear paradoxical and runs counter to previous studies, resources for predators may be predictably more limited than resources for herbivores, thus driving selection for more profitable prey.