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

MATHIASEN, P.; FASANELLA, M.; DIAZ, D.G.; JURI, G.; HASBÚN, R.; PREMOLI, A.C.

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

The southern tip of South America has a long and complex geological history, whichbegun with the breakup of Gondwana and was followed by global sea level rises,tectonic processes such as mountain building and volcanism, glaciations, and the associatedclimatic changes. The ancient ora of South America evolved under thesechanging environments. As a result, lineage diversication of long-lived woody taxa,such as Nothofagus, will reect the eects of the Paleogene paleogeography of Patagoniaand more recent climatic oscillations of the Neogene. The objective was toevaluate the phylogeographic patterns of Nothofagus dombeyi combining geologicalevidence from marine sedimentary basins, Andean orogeny, and climatology withphylogenetic and statistical analyses. A total of 203 individuals along the entirerange of distribution of the species were sampled and analyzed by sequencing threenon-coding regions of the chloroplast DNA. We found 24 chloroplast DNA haplotypesacross the range. The phylogenetic tree and the haplotype network yieldedthree strongly dierentiated lineages that were latitudinally structured (AMOVAPhiST1-2=0.692, PhiST1-3=0.928, PhiST2-3=0.904). Two phylogeographic breakswere observed at 39S and 42S. The groups identied by BAPS and the PCA analysiswere in agreement with the three lineages. Lineage divergence was concordantwith ancient geological events that took place during Eocene to Miocene epochs,while haplotype diversication within lineages was driven by more recent climaticchanges during the Pliocene. Middle-range Lineage 2 was the most polymorphic(67.11%), holding 15 of the 24 haplotypes, showing that marine transgressions (lateMiddle Miocene, Late Miocene, and Early Pliocene) could favor the great geneticdiversity. These ages have been assigned recently to Chilean formations near thePacic coast and across the Chilean Central Depression.