Phylogeography of an Endangered Disjunct Herb: Long-distance Dispersal, Refugia, and Colonization Routes

Current diversity patterns are influenced by both historic and recent environmental conditions. Quaternary glacial cycles appear to have had a consistent role in shaping the genetic diversity and structure of plant species. Yet 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. A recent study by Bobo-Pinilla et al., published as an Editor’s Choice article in AoBP, sought to reconstruct the phylogeographic patterns of intraspecific lineages within Astragalus edulis, with the general aim of contributing to the understanding of the biogeographic history of the western Mediterranean–Macaronesian area.

Distribution model of Astragalus edulis
Distribution models; Habitat suitability is represented by green-yellow to red. (Red-yellow = Medium, Green = High). A) Present; B) Last Glacial Maximum; C) Last Inter-Glacial. Dotted line represents the south to north colonization route along Morocco. Black dots represent current localities of the species. Image credit: Bobo-Pinilla et al.

Astragalus edulis is a disjunct endemic of the western Mediterranean-Macaronesian area. 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 modelled potential distribution of A. edulis under current conditions was projected over the climatic conditions of the Last Interglacial and Last Glacial Maximum to analyse changes in habitat suitability. The models suggested south-western Morocco as the ancestral area of the species,with subsequent colonization of north-eastern Morocco then the Iberian Peninsula.This route may have also been followed by other plant species, some of which are also endangered and with fragmented distributions.

Researcher highlight

Javier Bobo-Pinilla

Javier Bobo-Pinilla obtained a bachelor’s degree in biology from the University of Salamanca in 2010. In 2012, he completed a MSc. degree in biology and plant conservation. Javier now belongs to the BIOCONS research group (University of Salamanca). He is currently a PhD student under the supervision of Dr. M. Montserrat Martínez-Ortega (University of Salamanca) and Julio Peñas de Giles (University of Granada).

Javier is a botanist interested in plant conservation, phylogeny and of mediterranean endemic plants. He has worked with several endemic plants including Arenaria balearica, Arenaria suffruticosa and Astragalus edulis.

Reference List

Bobo-Pinilla, J., Peñas de Giles, J., López-González, N., Mediavilla, S., & Martínez-Ortega, M. M. (2018). Phylogeography of an endangered disjunct herb: long-distance dispersal, refugia and colonization routes. AoB PLANTS, 10(5). https://doi.org/10.1093/aobpla/ply047