Abstracts (first author)
A genetic approach of reef colonization by a surgeon fish (Acanthurus triostegus) in La Réunion Island
Resilience of coral reefs is highly dependent on the ability of reef organisms to colonize and survive, and thus to maintain these reefs connected. The aim of this study was to better understand, through population genetics, the fine-scale spatio-temporal colonization pattern of the surgeon fish A. triostegus. This species is well distributed all over the Indo-Pacific reefs and presents a good model to study the variability of reproductive success in marine organisms. The recruits, arriving in two locations 20 km apart, were collected from March 2011 to February 2013 using light traps. A total of 520 post-larvae were caught. Sampling was divided into several nested groups for each location: 4 reproduction seasons (mean duration: 3 months), 17 fishing campaign (6 days around the new moon), 64 days (whenever catches number was higher than 25 individuals). The genetic structure of these juveniles’ populations was assessed using 14 microsatellites loci. For a given location, we found no significant genetic differentiation (1) between days among a fishing campaign, (2) between fishing campaign among a reproduction season, and (3) between reproduction season (maximum FST = 0.0043, NS). On the 34 comparisons performed between locations over fishing campaign, only 4 were differentiated from the others (maximum FST = 0.012 ; P=0.042). Assignment tests did not allow identifying any genetic cluster over the overall sampling. These results showed the absence of temporal or spatial genetic heterogeneity between the post-larvae samples (no chaotic genetic patchiness): the pool of reproductive adults was stable through time. Moreover, the heterozygote deficiency (mean FIS = 0.153±0.006) can be linked to related fishes within samples. So, we performed sib-ship and half-ship reconstruction and found brothers and sisters among samples, showing that post-larvae migration is concerted. Key-words: colonization, A. triostegus, fish, population structure, microsatellites.