The origin of Rattus rattus on the Iles Eparses, Western Indian Ocean

Tollenaere et al. (Journal of Biogeography, 2010, 37, 398–410) present a phylogeographic analysis of Rattus rattus for the Western Indian Ocean, with particular emphasis on Madagascar, but do not include samples from three island groups centrally located in the Mozambique Channel. Haplotypes from these islands provide additional information on the colonization pathways of R. rattus in the Western Indian Ocean region. For each of the three Iles Eparses groups in the Mozambique Channel, we test the competing hypotheses that colonization by R. rattus was most likely: (1) from the Arabian Peninsula, (2) from East Africa, (3) from Madagascar, or (4) from independent shipping. These results are combined with historical observations of the presence of R. rattus on these islands to give stronger inference on the colonization pathways. Additionally, more accurate colonization dates provide guidance for contemporary conservation management.