Temporal congruence of replicated patterns of vicariance and range expansion in Patagonian lizards

MORANDO, M.; CARMARGO, A.; AVILA, L.J.; SITES, JR. J. W.

Bariloche

Congreso; VI Southern Connection; 2010

Universidad Nacional del Comahue-CONICET-INTA

Based on cytochrome-b data, there are replicated patterns in different clades of Patagonian lizards. Closely related haploclades are distributed North and South of the Somuncurá Plateau, suggesting a common vicariant event. We did comparative analyses in 5 lineages to test for temporal congruence based on the following taxa and sample sizes: L. bibronii N=50, S=50), H. darwinii (N=25, S=25), L. bellii (N=6, S=9), L. melanops (N=50, S=50), L. petrophilus (N=30, S=30). For three of these we tested for a simultaneous southern expansion: L. bibronii (N=46, S=50), L. fitzingerii (N=44 S=42), H. darwinii (N=23, S=37). We used MrBayes to estimate parameters for different models with 1 million simulations for each. For both patterns there is a strong signal for a single event that affected all lineages and occurred very recently (mean time ~6,000 y.a.) and probably simultaneously, or the southern expansion shortly after the N-S Somuncurá divergence. After the last glacial maximum, mean temperature increased rapidly and considerably and sea level rises covered the same amount of land now above sea level, likely pushing easternmost populations towards the west and south. As these populations encountered the Somuncurá Plateau, they split into northern and southern clades, and a third wave of migration further south into land previously covered by permafrost. In these lineages there is higher genetic diversity the east coast, supporting the idea of eastern refugia during glacial times.