Reconstruction of the colonization of southern Madagascar by introducedRattus rattus

Aim Description of the genetic differentiation ofRattus rattuspopulations in southern Madagascar. Reconstruction of the colonization pattern ofR. rattusin southern Madagascar and of the origin of introducedR. rattus. Location Southern Madagascar. Methods We analysed the variation in the non‐coding hypervariable region 1 (HVR I) of the mitochondrial control region in 93 individuals from six different sampling sites. The origin of the introduced individuals was examined by comparing MalagasyR. rattussequences to data available from outside Madagascar. Results Thirteen distinct mtDNA control region haplotypes (H1–H13) were distinguished. Only 11 sites (2.6%) were variable within a 419‐bp sequence. Three haplotypes were shared between the sampling areas, though only one haplotype was ubiquitous accounting for 63.4% of all individuals. Population genetic differences (ΦST) between sampling sites ranged from 0.13 to 0.31.amovaresults showed that the majority of variation (86.1%) was assigned to diversity within populations. Except for twoR. rattussequences from India, all other outgroup samples (New York, Great Britain, France and French Polynesia) belonged to an identical haplotype. Main conclusions The spatial distribution and frequency of haplotypes and associated phylogenetic analysis provisionally suggest the Tolagnaro harbour as the place of the founder population from whichR. rattusspread into southern Madagascar. Given currently available samples, these populations are most closely related to rats from the Indian subcontinent. Corroboration of each of these hypotheses will require additional geographical sampling, particularly from northern Madagascar and Africa.