How and when did Antarctic hairgrass reach Antarctica?

GONZALEZ L; AC PREMOLI; CHIAPELLA J; FASANELLA M; URDAPILLETA J

Congreso; International Plant Science Conference, the Botanikertagung 2017; 2017

Deschampsia antarctica is the only grass with disjunct distribution between Patagonia and Antarctica, offering a unique model to study evolution of disjunction. We studied genetics and cytogenetic aspects of populations of the entire distribution range. We collected data from 17 populations in Patagonia and six in Antarctica, and analyzed sequence variation of 144 individuals, ploidy level and genetic diversity and structure and tested the divergence time between regions. The Patagonian populations show greater variability in chromosomal and molecular characters than those from Antarctica. We found a significant divergence between Patagonia and Antarctica (cpDNA Fst = 0.518, p < 0.001; nDNA Fst = 0.823, p < 0.001). Larger number of private haplotypes and greater genetic and chromosomal variability in Patagonia support the hypothesis of a South American origin of the Antarctic populations, which are diploid, while in Patagonia also tetraploids were found. Divergence time between populations of the two regions was dated in the Mid-Late Pleistocene and dispersal occurred through bird-aided long-distance transport from S.America.