Gene flow of Acanthaster planci (L.) in relation to ocean currents revealed by microsatellite analysis

Abstract

Population outbreaks of the coral-eating starfish, Acanthaster planci, are hypothesized to spread to many localities in the Indo-Pacific Ocean through dispersal of planktonic larvae. To elucidate the gene flow of A. planci across the Indo-Pacific in relation to ocean currents and to test the larval dispersal hypothesis, the genetic structure among 23 samples over the Indo-Pacific was analysed using seven highly polymorphic microsatellite loci. The F-statistics and genetic admixture analysis detected genetically distinct groups in accordance with ocean current systems, that is, the Southeast African group (Kenya and Mayotte), the Northwestern Pacific group (the Philippines and Japan), Palau, the North Central Pacific group (Majuro and Pohnpei), the Great Barrier Reef, Fiji, and French Polynesia, with a large genetic break between the Indian and Pacific Oceans. A pattern of significant isolation by distance was observed among all samples (P = 0.001, r = 0.88, n = 253, Mantel test), indicating restricted gene flow among the samples in accordance with geographical distances. The data also indicated strong gene flow within the Southeast African, Northwestern Pacific, and Great Barrier Reef groups. These results suggest that the western boundary currents have strong influence on gene flow of this species and may trigger secondary outbreaks.

Limits to gene flow in a cosmopolitan marine planktonic diatom

“…Hence, our data strongly suggest that isolation by large distances allows for genetic divergence, even in high-dispersal organisms like planktonic diatoms. This is in line with other marine organisms, where similar patterns of significant IBD were observed from regional to global scales (23,(50)(51)(52).…”

“…Flow patterns of tidal or oceanic currents may also contribute to the genetic isolation among global populations by hindering dispersal (22,23,28,58,59). For example, there were no significant F ST values between populations from the North Sea and a connected Danish inland fjord, yet populations from the Irish Sea and the adjacent North Sea showed significant differentiation.…”

“…Population genetic surveys using high-resolution markers that allow differentiation among individuals, are greatly improving our understanding of the mechanisms that cause genetic diversity within and gene flow between populations (20). To date, population genetic studies of high-dispersal organisms in the marine environment have largely focused on pelagic or benthic animals with planktonic larval stages (21)(22)(23)(24). Population genetic structuring of planktonic microorganisms has been much less explored due to difficulties with species delineation and lack of finescale genetic markers for these organisms (25)(26)(27)(28).…”

Biogeographic origins of the viviparous sea snake assemblage (Elapidae) of the Indian Ocean

“…The highly significant F ST value for all ten microsatellite loci between the IO and WP populations (combined Phuket-Thailand, SEA, Australia), reciprocal monophyly in mitochondrial lineages, the clear separation of nuclear alleles and the population assignment findings strongly indicate the lack of contemporary gene flow between these populations despite the absence of current geographic/physical barriers for dispersal and gene flow. This lack of contemporary gene flow among IO and WP populations has also been demonstrated in many other reef-associated fauna (Yasuda et al, 2009;Leray et al, 2010). The habitat preference of shallow coastlines and the lack of larval stages that allow long distance dispersal may prevent sea snakes from crossing deeper seas and population connectivity reducing gene flow.…”

Phylogeography ofPadina boryana(Dictyotales, Phaeophyceae) around the Thai-Malay Peninsula

“…E-mail: wbongkot@gmail.com This lack of connectivity can be seen in the genetic differentiation of many organisms, for example, coral (Clifton, 1997;Knittweis et al, 2009), macroalgae (Maggs & Callow, 2002), crustaceans (de Bruyn et al, 2005;Obst et al, 2012) and plants (Liao et al, 2009). Moreover, molecular genetic analyses of anemone fish (Timm & Kochzius, 2008), seastars (Yasuda et al, 2009) and coral (Knittweis et al, 2009) have found a clear genetic break between Indian and Pacific Ocean populations, which has been attributed to the ocean current patterns in the region.…”