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Phylogeography at the crossroad: Pleistocene range expansion throughout the Mediterranean and back‐colonization from the Canary Islands in the legume Bituminaria bituminosa
Author(s) -
GarcíaVerdugo Carlos,
Mairal Mario,
Tamaki Ichiro,
Msanda Fouad
Publication year - 2021
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/jbi.14100
Subject(s) - phylogeography , ecology , range (aeronautics) , mediterranean islands , pleistocene , mediterranean climate , biology , taxon , biogeography , vicariance , geography , genetic diversity , population , paleontology , phylogenetic tree , demography , biochemistry , materials science , gene , composite material , sociology
Aim Species with widespread distributions offer excellent opportunities for investigating recent biogeographical patterns across broad scales. Here, we tested the hypothesis that, due to its intermediate geographical location, NW Africa is pivotal in explaining the phylogeographical patterns of taxa with Mediterranean–Macaronesian distributions using a legume species with short generation times. Location Mediterranean, with a focus on NW Africa and the Canary Islands. Taxon Pitch trefoil ( Bituminaria bituminosa ). Methods We generated genetic data and performed phylogeographical and demographic analyses at two geographical scales: Mediterranean Basin (MB), using plastid sequences (115 individuals), and Macaronesia, using plastid sequences (182 individuals) and 10 nuclear microsatellite loci (220 individuals). We also performed a literature survey focusing on phylogeographical studies of other circum‐Mediterranean taxa. Results Northwest Africa was identified as a centre of genetic diversity (19 out of 38 haplotypes) and demographic expansion of B. bituminosa in the MB during the Pleistocene. Our literature review revealed two main phylogeographical patterns in widespread species: pre‐Mediterranean evergreen sclerophylls versus Pleistocene facultative‐deciduous (including Bituminaria ) taxa, but on average, both functional groups show a similar, large genetic diversity (~40% of haplotypes) in NW Africa. At the Macaronesian scale, we found that Canarian Bituminaria is composed of two genetic sublineages that coexist and hybridize on the central islands and in the mainland Macaronesian enclave (Anti‐Atlas region). Demographic analyses rejected the progression rule as the model of island colonization but strongly suggested that Anti‐Atlas populations are the result of back‐colonization from the easternmost islands before the Last Glacial Maximum (LGM). Conclusions Bituminaria displays a pattern of Quaternary eastward expansion in the MB that appears to be paralleled by several members of its functional plant group. Thus, our study reveals a previously undescribed dual role of NW Africa in plant biogeography, acting both as a source of species expansion to the rest of the MB and a LGM refugium of plant populations with a Macaronesian island origin.