INVESTIGADORES
FASANELLA mariana
congresos y reuniones científicas
Título:
Genetic variation in the Antarctic hairgrass
Autor/es:
FASANELLA MARIANA; PREMOLI ANDREA ; CHIAPELLA JORGE
Reunión:
Simposio; VIII SOUTHERN CONNECTION CONGRESS; 2016
Resumen:
Deschampsia antarctica is the only grass with disjunct distribution between Patagonia and Antarctica, and offers a unique model to examine the relative contribution of vicariance and dispersal. We study the distribution of genetic polymorphisms along the entire range of D. antarctica to unravel its biogeographic history. We randomly collected leaf samples from 16 and 6 populations in South America and Antarctica, respectively. We sequenced a total of 144 individuals by nuclear nDNA ITS and chloroplast cDNA regions. We quantified genetic diversity (nucleotide and haplotype diversity) and structure (Fst, Mantel tests, and dated between-region divergence). Patagonia was undoubtedly the most genetically variable area (17 ITS and 8 cpDNA haplotypes) over Antarctica (1 ITS and 4 cpDNA haplotypes). We found a significant divergence between Patagonia and Antarctica (cpDNA Fst = 0.518 ± 0.012; nDNA Fst = 0.823 ± 0.001) and ITS sequences fit to isolation by distance. The divergence Antarctica-Patagonia was dated in the Middle Pleistocene (700.000-130.000 years) probably through bird-aided long-distance dispersal events. We hypothesize that D. antarctica probably survived the Last Glacial Maximum (LGM) in ice-free coastal refugia in Maritime Antarctica, nunataks or adjacent islands and when the climate was relatively favorable, the species achieved its present distribution range. Future work includes increasing of sampling from other Southern Seas islands such as Kerguelén or Malvinas islands.