Phylogeny and niche evolution of ocellated lizards

Aim: The ocellated lizards of the genus Timon, comprising six species that are distributed across continental Asia, Europe and Africa, offer an interesting model to study the evolution of ecological niches through  comparative phyloclimatic analysis. Our study provides insights into the evolutionary history of the ocellated lizards and helps to understand the role of climatic niche evolution during the speciation process.
Location Eastern and western margins of the Mediterranean basin.
Methods:  A dated molecular phylogeny was estimated based on three mitochondrial and two nuclear genes. Using multivariate statistics, species distribution models were developed to characterize the Grinnellian niches of all species. Subsequently, ancestral environmental niche occupancy of each taxon
was reconstructed using niche occupancy profiles. Niche divergence among species was quantified by computing multivariate niche overlaps via twodimensional and n-dimensional approaches.
Results: Phylogenetic analysis supports that the ancestor of Timon diverged into the eastern and western groups following multiple vicariance events that shaped the current distribution pattern of Palaearctic lizards. High complexity in the ecological niche evolution between the Mediterranean and non-Mediterranean climatic regions was detected. The generally low niche divergence among members of the eastern group and the remarkable climatic divergence within the western group highlight an important role of temperature seasonality in a Mediterranean and Atlantic climate context. The results also suggest niche conservatism in terms of microhabitats described by vegetation cover.
Main conclusions: The ocellated lizards provide an interesting example of a vertebrate radiation where niche shift (with or without vicariance) and niche conservatism alternate in different niche axes shaping current biogeographical patterns.