Microevolutionary trends of tooth complexity in the Ibiza wall lizard, Podarcis pityusensis, mirror macroevolutionary trends in squamates

Abstract

Tooth complexity has long been known as a powerful indicator of feeding in mammals and reptiles, often used to infer diets of long-extinct species. However, how these trends are established below the species level remains unclear. Here, we use Orientation Patch Count Rotated (OPCR) to quantify tooth complexity across eight populations of Podarcis pityusensis, an insular omnivorous lizard endemic to the Pityusic Islands of the Western Mediterranean. These populations vary widely in their extent of herbivory and specialisation, which we use to assess the link between complexity and diet. We find that increasing herbivory is matched with increasing dental complexity, with comparable effect sizes to those found on the macroevolutionary scale. We do not, however, find clear evidence of divergence of tooth complexity between sexes within populations (in a way that would be consistent with niche divergence), meaning that the extent to which this trait is plastic remains controversial. Our results suggest that dental complexity is a highly powerful metric to infer diet, and an informative candidate for linking micro- and macroevolutionary patterns.