Retracing the evolutionary history of Nothofagus in its geoclimatic context: new developments in the emerging field of phylogeology

ACOSTA, M. CRISTINA; MATHIASEN, PAULA; PREMOLI, ANDREA C.

GEOBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Año: 2014 vol. 12 p. 497 - 510

1472-4677

Evolution of woody species of Nothofagus traced by intra- and interspecific genetic patterns are often linked to vicariance and dispersal due to past configuration of Southern Hemisphere land masses. However, the effects of ancient landscapes associated to global sea level rises, tectonic processes, and climatology driving lineage evolution have been largely overlooked. These can be tested in widespread lineages of cold-tolerant species that have endured cooling and thus, phylogeographic patterns may reflect large-scale processes that were not reset by the ice ages. We combined molecular dating of widespread South American Nothofagus with geological and paleoclimate evidence to reconstruct distribution patterns, colonization routes, and past population expansion under landscape features that significantly differed to those at present. A total of 239 populations along the entire range of all species within subgenus Nothofagus (N. antarctica, N. betuloides, N. dombeyi, N. nitida , and N. pumilio) were sampled and analyzed by sequences of three non-coding regions of the chloroplast. We found thirty chloroplast DNA haplotypes which were geographically structured. Calibrated dating using fossils of the molecular phylogeny revealed that ancestral lineages appeared in EoceneOligocene whereas most divergences took place during the Miocene. Bayesian skyline plots showed that population expansion occurred at the Early Pleistocene (1.5-1 million years ago). Lineage divergence from all wide ranging Nothofagus was spatially and temporally concordant with episodic marine incursions and warmer times in Patagonia during the Upper Tertiary. Long-lasting stable raised areas preserved haplotype diversity throughout species? distributions from where cold-tolerant taxa expanded their ranges during pre-Quaternary times. The detailed study of such ancient divergences is novel and allows the delimitation of paleolandscape features inferred on the basis of the distribution of genetic variation, geological data, and paleoclimate reconstructions. Hence, dated intra- and interspecific genealogies may be a valuable tool for the geological reconstruction by molecular methods, i.e. phylogeology.