Genetic Population Structure of the Coral Reef Sea Star Linckia laevigata in the Western Indian Ocean and Indo-West Pacific

Abstract

The coral reef sea star Linckia laevigata is common on shallow water coral reefs of the Indo-West Pacific. Its large geographic distribution and comprehensive data from previous studies makes it suitable to examine genetic differentiation and connectivity over large geographical scales. Based on partial sequences of the mitochondrial cytochrome oxidase I (COI) gene this study investigates the genetic population structure and connectivity of L. laevigata in the Western Indian Ocean (WIO) and compares it to previous studies in the Indo-Malay-Philippines Archipelago (IMPA). A total of 138 samples were collected from nine locations in the WIO. AMOVA revealed a low but significant ΦST-value of 0.024 for the WIO populations. In the hierarchical AMOVA, the following grouping rejected the hypothesis of panmixia: (1) Kenya (Watamu, Mombasa, Diani) and Tanzanian Island populations (Misali and Jambiani) and (2) the rest of the WIO sites (mainland Tanzania and Madagascar; ΦCT = 0.03). The genetic population structure was stronger and more significant (ΦST = 0.13) in the comparative analysis of WIO and IMPA populations. Three clades were identified in the haplotype network. The strong genetic differentiation (ΦCT = 0.199, P < 0.001) suggests that Indo-West Pacific populations of L. laevigata can be grouped into four biogeographic regions: (1) WIO (2) Eastern Indian Ocean (3) IMPA and (4) Western Pacific. The findings of this study support the existence of a genetic break in the Indo-West Pacific consistent with the effect of lowered sea level during the Pleistocene, which limited gene flow between the Pacific and Indian Ocean.

Comparative phylogeography of three host sea anemones in the Indo‐Pacific

“…This is a main limitation to draw general conclusions when comparing patterns of genetic structure that can only be resolved through better coordination among research groups. Our results are in agreement with previous studies and suggest that genetic exchange among eastern and western Indian Ocean might be limited by the presence of only a few islands that could facilitate connectivity via island hopping (Otwoma & Kochzius, ; Sheppard et al, ). The Maldives seems to be one of these important crossroads where different lineages meet.…”

“…We found that there is a significant congruence of patterns of genetic differentiation among species and that the Maldives (western/central Indian Ocean) represents a location of overlap or possible hybridization among distinct anemone populations or lineages (Sheppard et al, ). Previous studies have reported genetic discontinuity between the eastern and western Indian Ocean in different taxa including coral reef fishes (Bay, Choat, van Herwerden, & Robertson, ; Gaither et al, ; Huyghe & Kochzius, ; Leray et al, ) and invertebrates such as echinoderms (Otwoma & Kochzius, ; Vogler et al, ) and giant clams (Hui et al, ). Only one of these included samples from the Maldives (Vogler et al, ) and did not report overlap of different clades at these islands.…”

Seascape genetics of the spiny lobster Panulirus homarus in the Western Indian Ocean: Understanding how oceanographic features shape the genetic structure of species with high larval dispersal potential

“…It also receives waters from the East African Coastal Current along coastal Tanzania and Kenya. Water from the South Equatorial Current enters the northern Mozambique Channel, forming a series of eddies which propagate southwards through the channel (Halo et al, ; Otwoma & Kochzius, ). These waters are augmented by eddies originating from the East Madagascar Current at the southern end of the channel (de Ruijter et al, ; Ridderinkhof, Bars, Heydt, & Ruijter, ), and their confluence forms the upper Agulhas Current off southern Mozambique and eastern South Africa.…”

“…It also receives waters from the East African Coastal Current along coastal Tanzania and Kenya. Water from the South Equatorial Current enters the northern Mozambique Channel, forming a series of eddies which propagate southwards through the channel (Halo et al, 2017;Otwoma & Kochzius, 2016).…”

Revisiting the “Centre Hypotheses” of the Indo‐West Pacific: Idiosyncratic genetic diversity of nine reef species offers weak support for the Coral Triangle as a centre of genetic biodiversity

“…Our EBSP results together with Tajima's D indicate population expansions for most of the studied species (Appendix S9). Expansions were also suggested for honeycomb grouper (Muths et al., ), humbug damselfish (Liu et al., ), blue sea star (Otwoma & Kochzius, ), using mismatch distribution and/or Harpending's R analyses, and for threadfin butterflyfish (DiBattista et al., ) and whitecheek surgeonfish (DiBattista et al., ) by directly estimating the time of expansions. Although the general signal for expansion can be taken as a support for Survival (Table ), locations of population expansions are inconsistent across species.…”