Cependant, de forts FIS et des déséquilibres de liaisons significatifs sur collecteurs suggèrent qu'un faible nombre de géniteurs sont à l'origine des cohortes recrutées. Le collectage semble donc permettre un bon échantillon de la variabilité génétique disponible à l'état sauvage.
Dans cette étude, la variabilité génétique observée sur collecteurs n'est pas significativement différente de la variabilité génétique de la population sauvage de référence. Les niveaux de variabilité génétique observés en fermes et en milieu naturel ne sont pas significativement différents. Cette évolution en vingt ans suggère un fort succès reproducteur dans les fermes et donc une forte contribution des géniteurs de fermes à la constitution de la génération « sauvage" suivante. Dans des études précédentes, l'utilisation de marqueurs moléculaires a montré une homogénéisation de la composition génétique des stocks de plusieurs îles de deux archipels entre lesquelles des translocations massives ont été pratiquées. Le recrutement étant sporadique spatio-temporellement, le naissain est couramment transféré entre atolls. L'exploitation de l'huître perlière Pinctada margaritifera, développée en Polynésie depuis vingt ans, repose principalement sur le captage de naissain naturel.
Although these results are based on a limited number of locus and deserve to be confirmed with more variable markers, the cumulative effect of this phenomenon at each generation could induce a loss of genetic variability on a long term basis. This could mean that animals cultivated on the farms are more likely to be related or inbred than those in the wild. Nevertheless, high values of linkage disequilibrium and Fis on these spat "collecting stations" suggest that only a small number of spawners are in reality the parents of the collected spat. This tends to indicate that spat from "collecting stations" is efficient in sampling the genetic variability available in the wild. In This study we show that the genetic variability (number of alleles and expected heterozygosity) observed on spat "collecting stations" and in the wild populations are not significantly different. We used the same markers to show that the level of genetic variability observed on farms is not significantly different to that observed in the wild. This suggests a high level of reproductive success on farms, which is likely to be due to the high density of animaIs when compared to the density in the wild. In previous studies, anonymous nuclear markers demonstrated that This development has coincided with a genetic homogenisation of the wild stocks since the 1980s. Recruitment is highly variable in space and time and so spat is very often transferred by the farmers between atolls or even between archipelagos. However, a more accurate picture of the situation might be obtained with more variable markers.Įxploitation of the pearl oyster Pinetada margaritifera, which has developed in French Polynesia over the last twenty years, is based mainly on the collection of natural spat.
No significant differences were found between wild and adjacent farmed populations for the number of alleles and observed heterozygosity, which supports the conclusion that current methods used to collect wild spat are unlikely to affect the genetic composition of pearl oyster populations. This suggests that large-scale dispersal, either due to the absence of barriers to natural larval migration, or to the transport of collected spat for pearl production.
No genetic difference was observed among samples from wild populations collected from Northern Tuamotu to Southern Gambier. In this study, we analysed the structure of genetic variability, in wild and farmed populations distributed on four atolls from the Tuamotu–Gambier archipelago using four anonymous nuclear loci. A good knowledge of these resources is thus essential for the rational management of farmed and wild populations. Production relies almost exclusively on the collection of wild spat, which makes the activity very dependent on natural resources. Pearl production, based on the aquaculture of the blacklipped pearl oyster Pinctada margaritifera, is an essential economic activity in French Polynesia.
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