Restricted gene flow among western Indian Ocean populations of the mangrove whelk Terebralia palustris (Linnaeus, 1767) (Caenogastropoda: Potamididae)
Ratsimbazafy, H.A.; Kochzius, M. (2018). Restricted gene flow among western Indian Ocean populations of the mangrove whelk Terebralia palustris (Linnaeus, 1767) (Caenogastropoda: Potamididae). J. Moll. Stud. 84(2): 163-169. https://dx.doi.org/10.1093/mollus/eyy001
In: Journal of Molluscan Studies. Oxford University Press: Reading. ISSN 0260-1230; e-ISSN 1464-3766, more
To investigate gene-flow patterns in the western Indian Ocean (WIO), tissue samples of Terebralia palustris were collected along the coasts of East Africa and Madagascar. A fragment of the mitochondrial cytochrome c oxidase subunit I (COI) gene was sequenced in 308 individuals from 18 sites. Based on a COI fragment of 624 base pairs, 43 haplotypes were identified. The two most abundant haplotypes were shared among all sample sites, but 20.9% of the haplotypes were restricted to the sites in southern Mozambique. Population expansion was found and confirmed by moderate haplotype diversity, low nucleotide diversity and the analysis of demographic history. Analysis of molecular variances (AMOVA) revealed significant genetic differentiation among populations (φst = 0.10, P ≤ 0.001). Pairwise φst and a hierarchical AMOVA (φct = 0.04, P = 0.01) suggest significant genetic differentiation among five regions: (1) northern Kenya, (2) Kenya, Tanzania and western Madagascar, (3) northeastern Madagascar, (4) southern Madagascar and (5) southern Mozambique. Since the analysis of isolation by distance did not show a significant correlation between geographic distance and genetic differentiation, even though the maximum distance between sites is about 3,050 km (Z = 7,513.89, r = 0.12, P = 0.08), the complex oceanography in the WIO could be the main factor that restricts gene flow.
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