Evolution of niche and ecomorphological traits in a phylogenetic context in lizards of the Liolaemus bibroni complex (Squamata: Liolaemini)

EDWARDS, D.L.; MARTINEZ, L.E.; AVILA, L.J.; SITES, J.W., JR.; MORANDO, M.

Congreso; X Congreso Latinoamericano de Herpetologia; 2014

The South American lizard genus Liolaemus is now considered a radiation with more than 240 described species. One of the most interesting clades is the Liolaemus bibronii complex, which inhabits a great diversity of habitats, including the Monte, Steppe, and high Andean grassland environments over a large geographic distribution (1 million km2). Taxonomically this group includes two morphologically recognized species, but a mitochondrial-based phylogeographic study hypothesized that it may include up to 18 candidate species, and a morphological study showed statistical differences between most of these lineages. Here, we studied the evolution of niche and ecomorphological traits in the L. bibronii complex and closely related species (L. cyaneinotatus, L. saxatilis, L. ramirezae and L. robertmertensi). We used 415 individuals from 165 localities throughout the known distributional range. We sequenced cyt-b for all individuals, and for representatives of each haploclade we sequenced another mt marker (12S, total mt-markers: 1602 bp) and four nuclear anonymous markers (LPA11E, LPB4G, LPB9C, LPB11E: 3103bp) to construct a concatenated molecular tree. We measured six standard ecomorphological variables (SVL, axilla-groin length, head length, head width, number of finger and toe lamellae), and used niche data from global climatic databases and vegetation variables derived from satellite image data. Treating each lineage separately, we used comparative phylogenetic analyses to look at 1) how niche and ecomorphological traits have evolved through time (i.e., using disparity-through-time analyses), and 2) whether or not ecomorphological trait evolution is correlated with niche evolution (phylogenetic correlation). The morphological disparity analyses showed clear evidence of increasing diversification (greater than null disparity) towards the present in ecomorphology and vegetative niche, with correlated evolution of these traits. The same pattern is observed in elevation and climatic (but lacking correlated evolution) niche considering the median species tree, but when we accounted for phylogenetic uncertainty results showed low or no statistical support. Similarly to what was found for Australian desert lizards, we hypothesize that morphological and ecological diversification of this complex was associated with the development and diversification of arid habitats.