Phylogeography of an endangered disjunct herb: long-distance dispersal, refugia and colonization routes
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AuthorBobo Pinilla, Javier; Peñas de Gilés, Julio; López González, Noemí; Mediavilla, Sonia; Martínez Ortega, M. Monserrat
Oxford University Press
AFLPAstragalus edulisPalaeogeographical modelsWestern Mediterranean–Macaronesian areaPhylogeographyPlastid DNA
Bobo-Pinilla J, Peñas de Giles J, López-González N, Mediavilla S, Martínez-Ortega MM. 2018. Phylogeography of an endangered disjunct herb: long-distance dispersal, refugia and colonization routes. AoB PLANTS 10: ply047
SponsorshipThis work has been financed by the Spanish Ministerio de Ciencia e Innovación through the projects CGL2012- 32574 and REN2003-09427, as well as by the Andalusian Consejería de Innovación, Ciencia y Tecnología through the project RNM1067. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.
Quaternary glacial cycles appear to have had a consistent role in shaping the genetic diversity and structure of plant species. Despite the unusual combination of the characteristics of the western Mediterranean– Macaronesian area, there are no studies that have specifically examined the effects of palaeoclimatic and palaeogeographic factors on the genetic composition and structure of annual herbs. Astragalus edulis is a disjunct endemic found in the easternmost Canary Islands and the semi-arid areas of north-eastern Africa and south-eastern Iberian Peninsula. This endangered species shows no evident adaptations to long-distance dispersal. Amplified fragment length polymorphism (AFLP) data and plastid DNA sequences were analysed from a total of 360 individuals distributed throughout the range of this species. The modelled potential distribution of A. edulis under current conditions was projected over the climatic conditions of the Last Interglacial (130 ka BP) and Last Glacial Maximum (21 ka BP) to analyse changes in habitat suitability and to look for associations between the modelling and genetic results. Amplified fragment length polymorphism analysis showed clear phylogeographic structure with four distinct genetic clusters. Approximate Bayesian computation (ABC) models based on plastid DNA sequences indicated a Middle Pleistocene long-distance dispersal event as the origin of the populations of the Canary Islands. The models also suggested south-western Morocco as the ancestral area for the species, as well as subsequent colonization of north-eastern Morocco and the Iberian Peninsula. The data compiled indicated the possibility of the presence of refuge areas at favourable locations around the High Atlas and Anti-Atlas mountain ranges. Moreover, palaeodistribution models strongly support the events inferred by ABC modelling and show the potential distribution of the species in the past, suggesting a putative colonization route.