Retracing the evolutionary history of Nothofagus in its geo-climatic context: new developments in the emerging field of phylogeology

ACOSTA M.C., P. MATHIASEN & A.C. PREMOLI

GEOBIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 12 p. 497 - 510

1472-4677

Phylogeographic studies have made a significant contribution to unravel distribution shifts in response to changes in climate such as during glaciation events of the Neogene. 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 hereby combine geological evidence from marine sedimentary basins, Andean orogeny, and climatology with molecular dating and statistical phylogeography in order to infer how geological and climatic processes affected the distribution of lineages in cold-tolerant Nothofagus species during the Cenozoic. A total of 239 populations along the entire range of all species within Nothofagus genus (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 Eocene-Oligocene whereas most divergences took place during the Miocene while 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 transgressionss and warmer times in Patagonia during Eocene-Miocene Epochs. Long-lasting stable raised areas preserved haplotype diversity throughout Patagonia from where cold-tolerant taxa expanded their ranges during pre-Quaternary times. The detailed study of such ancient divergences is novel and allows to infer the effects of geological processes on distribution patterns of ancient lineagesi.e. phylogeology.