Glacial survival in and recent long-distance dispersal to the Iberian Mountains: the phylogeographic history of Artemisia umbelliformis (Asteraceae)

13 p., tablas, mapas -- Postprint del artículo publicado en Botanical Journal of the Linnean Society. Versión revisada y corregida --Artemisia umbelliformis is a herbaceous perennial alpine plant growing in the central and western part of the European Alpine system (Sierra Nevada, Cantabrian Mountains, Pyrenees, Alps and Apennines). We aimed to unravel the large-scale phylogeographic structure across its distribution. To this end, we collected amplified fragment length polymorphism and plastid DNA sequence data for 19 populations covering the distribution of the species. Populations were strongly reciprocally differentiated with 93% of the overall genetic variation partitioned among populations. Bayesian clustering approaches identified two groups: the Alpine group spanning the Alps, the Apennines and the Sierra Nevada and the northern Iberian group including populations from the Pyrenees and the Cantabrian Mountains. The three plastid haplotypes discovered fell into two strongly divergent clades, termed Iberian and Alpine lineages. At the range-wide scale, our results suggest that an early vicariance or, alternatively, an old dispersal event shaped the strong phylogeographic split between Iberian and Alpine populations. Genetic drift caused by highly restricted gene flow between the populations has probably resulted in reduced genetic variability and strong divergence between populations. The Alps, the central Pyrenees, the Cantabrian Mountains and the northern Apennines probably acted as glacial refugia for A. umbelliformis. In contrast, the single population occurring in the Sierra Nevada appears to originate from a fairly recent long-distance dispersal event from the southern central Alps. Altogether, our study shows that the phylogeographic history of A. umbelliformis is complex and has been shaped by processes acting at different time horizons. These processes conferred genetic relationships among disjunct populations, which partly reflected geographical proximity and partly spanned distant mountain ranges such as the Alps and the Sierra Nevada.This work was financed by projects CGL2004-04563-C02-02/BOS, CGL2010-2234-C02-01, CGL2010-2234-C02-02 and CGL2010-18631 from the Spanish Science and Technology Ministry and by 2009/SGR/439 and 2014/SGR/514 from the Generalitat de Catalunya.Peer reviewe