Evolution of herbivory in lacertid lizards: Effects of insularity and body size

I tested the putative correlation between insularity and herbivory in lacertid lizards. Analysis of literature data on 97 populations of 52 species shows that lizard populations on islands more often include plant material in their diet than do mainland populations. To investigate whether this finding reflects adaptation due to recent selection or is merely a product of the phylogenetic history of the populations, I reconstructed the ancestral states for diets and insularity and incorporated them in the analysis. Changes in habitat (island-mainland or mainland-island) often went with changes in diet (herbivore-insectivore or insectivore-omnivore). Insectivorous lizards that find themselves on islands more often turn towards herbivory than do lizards living in mainland situations. Lizards that already have plants in their diet when living on the mainland seem more successful in colonizing islands. Herbivorous populations of lacertids tend to be larger than insectivorous populations, but there is considerable overlap No difference in mean snout-vent length was found between island and mainland populations.