Phylogeography and palaeomodelling of Duseniella patagonica (Barnadesioideae), an early-diverging member of Asteraceae endemic to the Argentinean Monte and Patagonia

Abstract

We performed an integrated phylogeographical and palaeoclimatic study of an early-diverging member of Asteraceae,Duseniella patagonica, endemic to Argentina. Chloroplast and nuclear markers were sequenced from 106 individualsbelonging to 20 populations throughout the species range. We analysed genetic spatial distribution, diversity andstructure, tested for range expansion, estimated divergence times, reconstructed ancestral areas and modelled presentand past species distributions based on climatic data. Duseniella diverged from its sister genera during the Late/Middle Miocene. Its ancestral area included southern Monte plus eastern and central Patagonia. A vicariant eventseparated Monte and Patagonian clades during the Plio-Pleistocene. This would have involved unfavourable climate,soil, elevation, volcanism and/or other geomorphological processes between 40 and 43.5°S, in the sourroundings ofthe Somuncura plateau. Each clade possesses its own haplotypes and nucleotypes. Two populations, one in southernMonte and the other in eastern Patagonia, contain the highest diversity and exclusive haplotypes, representinghypothetical ancestral refugia. Northern Monte and southern Patagonian populations show low to null geneticdiversity, being the most recently colonized areas. Climatic models indicate that winter temperature influencedthe distribution of Duseniella, with an increase in probability of occurrence during colder periods, thus enablingdiversification during glacial episodes.