Phylogeography of Nothofagus dombeyi reflects past geological and climatic changes in southern South America

MATHIASEN PAULA; FASANELLA MARIANA; DIAZ DAYANA; JURI GABRIELA; HASBÚN RODRIGO; ANDREA CECILIA PREMOLI

Congreso; II Virtual Meeting of Systematics, Biogeography, and Evolution; 2021

The southern tip of South America has a long and complex geological history, which begun with the breakup of Gondwana and was followed by global sea level rises, tectonic processes such as mountain building and vulcanism, glaciations and the associated climatic changes. The ancient flora of South America evolved under these changing environments. As a result, lineage diversification of long-lived woody taxa, such as Nothofagus, will reflect the effects of the Paleogene paleogeography of Patagonia and more recent climatic oscillations of the Neogene. The objective was to evaluate the phylogeographic patterns of Nothofagus dombeyi combining geological evidence from marine sedimentary basins, Andean orogeny, and climatology with phylogenetic and statistical analyses. A total of 203 individuals along the entire range of distribution of the species were sampled and analyzed by sequencing three non-coding regions of the chloroplast DNA. We found 24 chloroplast DNA haplotypes, the phylogenetic tree and the haplotype network yielded three strongly differentiated lineages that were latitudinally structured (Phist1-2=0.692, Phist1-3=0.928, Phist2-3=0.904). Phylogeographic breaks were at 39°S and 42°S. The groups identified by BAPS and the PCA analysis were concordant with the three lineages. Lineage divergence was concordant with ancient geological events that took place during Eocene to Miocene periods, while haplotype diversification within lineages was driven by more recent climatic changes during the Pliocene. Middle-range Lineage 2 was the most polymorphic (67.11%), with 15 of the 24 haplotypes, showing that marine transgressions (late Middle Miocene, Late Miocene, and Early Pliocene), could favored the great genetic diversity. These ages have been assigned recently to Chilean formations near the Pacific coast and along the Chilean Central Depression.