Restricted dispersal of the reef fish Myripristis berndti at the scale of the SW Indian Ocean

The reef fish Myripristis berndti (Jordan & Everman 1903) is a pantropical species. A genetic analysis was conducted on 353 individuals from 10 localities distributed across the SW Indian Ocean (SWIO) in order to determine patterns of connectivity in the SWIO. Both the mtDNA sequences (711-bp cytochrome b sequences) and the microsatellites (8 newly developed loci) reveal spatial patterns of differentiation within the SWIO. There is, however, a discrepancy between the structure observed with each kind of marker. MtDNA revealed that 3 peripheral populations (NW Kenya, SE Reunion, and SW Europa) were isolated from the 7 more central populations, which form a more densely connected population network, while microsatellite data indicated a more restricted connectivity with significant differentiation between most pairs of localities. Higher genetic differences between Reunion and Europa were found, which might be explained by geography and isolation by distance pattern. In contrast, the genetic signature of Kenya-the most divergent locality identified by mtDNA basis but not with microsatellite-was probably the consequence of a particular colonisation history. These results indicate a much more restricted connectivity than previously thought for this species.