EVALUATING THE INFLUENCE OF TECTONICS ON THE GENETIC LINEAGE DISTRIBUTION OF NOTHOFAGUS IN CONTRASTING AREAS OF THE PATAGONIAN ANDES

BECHIS, F.; ACOSTA, M.C.; MATHIASEN, P.; PREMOLI, A.C.; THOMSON, S.; RAMOS, V.A.

Punta Arenas

Congreso; VIII Southern Connection Congress; 2016

The Northern and Southern Patagonian Andes show important differences regarding their geological evolution during the Cenozoic Era, which began 66 million years ago. These include important variations in the altitude, style and timing of the mountains? uplift, and the Pacific vs. Atlantic origin of marine connections, among others. Coincidentally, the geographic distribution of the genetic lineages and haplotypes found for all species within the genus Nothofagus also show important variations between the southern and northern sectors of the Patagonian Andes. Molecular dating has revealed that divergences of the ancestral lineages took place in different times during the Cenozoic associated with paleogeographic changes related to geologic and climatic factors. These previous studies proved that there is a strong link between the tectonic and biological evolution in Patagonia. In this contribution, we outline major latitudinal differences in the geologic evolution of the Patagonian Andes in order to identify key paleogeographic elements that could have acted as barriers, filters or corridors for the dispersion and divergence of Nothofagus species during the Cenozoic. Furthermore, we explore if the available genetic data could help to evaluate competing geological hypotheses, including the location of the Atlantic-Pacific marine connections, or the timing of the Andean uplift. We will particularly focus on the segment between 41° and 42°S, where a complete set of previous and new ages obtained from different techniques (apatite fission track thermochronology and U-Pb LA-ICPMS geochronology) allows a precise dating of the tectonic and paleogeographic evolution, favoring its comparison and integration with the genetic data.