Population Structure Of Pollinating Wasp Of Ficus Pumlia (Wiebesia Sp.3) In The Zhoushan Archipelago

Population structure has a profound effect on evolution process of a species. Understanding the population structure will do benefit to have knowledge of evolution history. Effective population size is an important indicator of genetic drift, whereas gene flow mitigates detrimental effects of genetic drift. Different levels of gene flow can result in several population structures, including, classical metapopulation, source-sink population and patchy population. Furthermore, comparisons of effective population size or gene flow among different temporal scales may have critical implications for understanding historical and contemporary processes underlying population structure.Wiebesia spp. and its pollinated plant (Ficus pumlia) consist a tightly integrated mutualism, since the wasp is the only pollinator of the fig and the wasp can not oviposit but inside the fig. Thus, understanding the population structure of Wiebesia spp. is also important to the persistence of the figs. Wiebesia spp. consists of three cryptic species. Wiebesia sp.3 is an inferior competitor relative to Wiebesia sp.1, which has a sympatric distribution with Wiebesia sp.3. This may make Wiebesia sp.3 much more prone to extinction.Here we estimated the genetic structure, effective population size as well as historical and contemporary gene flow by genotyping 8 microsatellite loci for 321 individuals from 8 Wiebesia sp.3 populations in Zhoushan of Zhejiang, China. Population DJ was found to have the lowest genetic diversity while population LH had the highest. Genetic divergence among populations was low and no isolation by distance was observed, when DJ was excluded. All populations were expected to form a single genetic cluster. Estimates of historical gene flow were lower than those of contemporary gene flow, while historical effective population sizes were higher than contemporary ones. Based on these results, several conclusions could be made as follows.1) The genetic differentiation among all the local populations was small, with an exception of DJ, which had the lowest genetic diversity.2) Historical effective population sizes were much higher than contemporary ones, caused by historical events. So that it's impossible for any local population to become extinction randomly in recent years. This will be good for the population persistance.3) The population structure of Wiebesia sp.3 conformed to a source-sink model, with DJ as the only source population. The structure of sink populations is coincident with the model of patchy population. All the sink populations could be sustained by the source population. Patchy population suggested that the population could be maintained for a long time. These results gave supports to long-term persistence of Wiebesia sp.3 populations.