Paleolandscape reconstruction based on DNA sequences of widespread Nothofagus

M. CRISTINA ACOSTA, PAULA MATHIASEN, ANDREA PREMOLI

Congreso; . IUFRO Landscape ecology Conference. Sustaining humans and forests in changing landscapes: Forests, society and global change; 2012

Phylogeographic analysis of widespread South American Nothofagus species in combination with molecular dating and geological data provide the natural setting to reconstruct paleolandscape features and species distribution patterns, including past population expansions. A total of 156 populations along the entire distribution range of four species of subgenus Nothofagus (N. antarctica, N. betuloides, N. dombeyi, and N. nitida) which grow predominantly in lowland Patagonia were sampled and analyzed by DNA sequences of three non-coding regions of the chloroplast. Twenty-eight chloroplast DNA (cpDNA) haplotypes were found that were significantly correlated with geographic distance. Molecular dating on the haplotype phylogeny revealed that most chloroplast variants were shared by all species which date back to Eocene-Miocene and long-lasting paleobasins and marine ingressions impeded transoceanic dispersal. A Bayesian skyline plot showed that the lineages of all species suffered a last bottleneck at the limit of Pliocene-Pleistocene, and they expanded after the Great Patagonian Glaciation. These results show that species of subgenus Nothofagus consist of ancient lineages that evolved during Tertiary times and that survived in situ throughout Patagonia.