Genetic population structure of the coral reef starfish Linckia laevigata in the Indo-West Pacific
Otwoma, L. (2012). Genetic population structure of the coral reef starfish Linckia laevigata in the Indo-West Pacific. MSc Thesis. VUB: Brussel. 66 pp.
The blue starfish Linckia laevigata is common on shallow water coral reefs of the Indo-West Pacific. Since L. laevigata is sedentary, long distance dispersal is only possible by their planktonic larval stage. This long larval dispersal mechanism can allow interconnection of populations that are separated by several hundred kilometers. However, a growing number of studies report genetic breaks in populations of L. laevigata across the Indo-Malay Archipelago and between the Indian and Pacific Oceans. Only limited information on the genetic connectivity of this species is available for the Indian Ocean, showing genetic structuring between samples collected in South Africa and Thailand. The study investigates the genetic population structure and connectivity of L. laevigata in the Western Indian Ocean and compares it to previous studies in the Indo-Malay Archipelago by mitochondrial cytochrome oxidase I gene. A total of 138 samples were collected from nine locations in the WIO coastline, from Kenya to Madagascar. AMOVA revealed a low but significant FST value of 0.024 in the WIO population, which indicated reduced gene flow. The genetic structure was stronger (FST = 0.13) in the comparative analysis of WIO and Indo-Malay Archipelago population. Five clades were detected from the haplotype network analysis which corresponded to different geographical locations that might have been separated during the glacial sea level low stands in the Pleistocene. The strong genetic differentiation suggests that the population of Linckia laevigata can be classified in the following groups: (1) Western Indian Ocean (2) Eastern Indian Ocean (3) Central Indo-Malay Archipelago and (4) Western Pacific.
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