Pleistocene colonization of afro-alpine 'sky islands' by the arctic-alpine Arabis alpina

• Published in: Heredity
• Main Authors: Assefa, A., Ehrich, D., Taberlet, P., Nemomissa, S., Brochmann, C.
• Other Authors: Department of Biology, Addis Ababa University (AAU), National Centre for Biosystematics (NCB), University of Oslo (UiO), Laboratoire d'Ecologie Alpine (LECA), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2007
• Subjects: afro-alpine; phylogeography; East Africa; cpDNA; Arabis alpina; pleistocene; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; [SDV.BID]Life Sciences [q-bio]/Biodiversity; [SDV.EE]Life Sciences [q-bio]/Ecology; environment; Arctic; Muleta
• Online Access: https://hal.archives-ouvertes.fr/halsde-00276507; https://doi.org/10.1038/sj.hdy.6800974

Times Cited: 0 International audience The afro-alpine region comprises the high mountains of Ethiopia and tropical East Africa, which represent biological 'sky islands' with high level of endemism. However, some primarily arctic-alpine plants also occur in the afro-alpine mountains. It has been suggested that these plants are Tertiary relicts, but a recent worldwide study of Arabis alpina suggests that this species colonized the region twice during the Pleistocene. Here we investigate the detailed colonization history of A. alpina in the afro-alpine region based on chloroplast DNA sequences from 11 mountain systems. The results confirm the twice-into-Africa scenario. The Asian lineage is confined to the mountains closest to the Arabian Peninsula, on opposite sides of the Rift Valley (Simen Mts and Gara Muleta in Ethiopia), suggesting long-distance dispersal of this lineage. The African lineage is divided into two phylogeographic groups with distinct geographic distribution. The observed pattern is consistent with isolation of the African lineage in at least two interglacial refugia, located on separated highlands, followed by range expansion in cooler period(s), when the afro-alpine habitat extended further down the mountains. Several long-distance dispersal events, also across the Rift Valley, are suggested by single haplotypes observed outside the area occupied by the phylogeographic groups they belonged to.