Combining the analysis of spatial and temporal variation when investigating population structure enhances our capacity for unravelling the biotic and abiotic factors responsible for microevolutionary change. This work aimed at measuring the spatial and temporal genetic structure of populations of the freshwater snail Biomphalaria pfeifferi (the intermediate host of the trematode Schistosoma mansoni) in relation to the mating system (self-fertilization), demography, parasite prevalence and some ecological parameters. Snail populations were sampled four times in seven human-water contact sites in the Man region, western Côte d’Ivoire, and their variability was measured at five microsatellite loci. Limited genetic diversity and high selfing rates were observed in the populations studied. We failed to reveal an effect of demographic and ecological parameters on within-population diversity, perhaps as a result of a too small number of populations. A strong spatial genetic differentiation was detected among populations. The temporal differentiation within populations was high in most populations, though lower than the spatial differentiation. All estimates of effective population size were lower than seven suggesting a strong effect of genetic drift. However, the genetic drift was compensated by high gene flow. The genetic structure within and among populations reflected that observed in other selfing snail species, relying on high selfing rates, low effective population sizes, environmental stochasticity and high gene flow.

中文翻译：

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科特迪瓦西部 Man 的淡水蜗牛 Biophalaria pfeifferi 的时空种群遗传结构，相对于人口和生态特征

在调查种群结构时结合对时空变化的分析，增强了我们解开导致微进化变化的生物和非生物因素的能力。这项工作旨在测量淡水蜗牛 Biophalaria pfeifferi（曼氏吸虫的中间宿主）种群的时空遗传结构与交配系统（自体受精）、人口统计学、寄生虫流行率和一些生态参数的关系。在科特迪瓦西部曼地区的七个人与水接触地点对蜗牛种群进行了四次采样，并在五个微卫星位点测量了它们的变异性。在研究的种群中观察到有限的遗传多样性和高自交率。我们未能揭示人口和生态参数对种群内多样性的影响，这可能是由于种群数量太少。在种群之间检测到强烈的空间遗传分化。大多数种群内的时间分化程度较高，但低于空间分化程度。有效种群大小的所有估计值均低于 7，表明遗传漂变的影响很大。然而，高基因流补偿了遗传漂变。种群内和种群间的遗传结构反映了在其他自交蜗牛物种中观察到的情况，依赖于高自交率、低有效种群规模、环境随机性和高基因流。在种群之间检测到强烈的空间遗传分化。大多数种群内的时间分化程度较高，但低于空间分化程度。有效种群大小的所有估计值均低于 7，表明遗传漂变的影响很大。然而，高基因流补偿了遗传漂变。种群内和种群间的遗传结构反映了在其他自交蜗牛物种中观察到的情况，依赖于高自交率、低有效种群规模、环境随机性和高基因流。在种群之间检测到强烈的空间遗传分化。大多数种群内的时间分化程度较高，但低于空间分化程度。有效种群大小的所有估计值均低于 7，表明遗传漂变的影响很大。然而，高基因流补偿了遗传漂变。种群内和种群间的遗传结构反映了在其他自交蜗牛物种中观察到的情况，依赖于高自交率、低有效种群规模、环境随机性和高基因流。有效种群大小的所有估计值均低于 7，表明遗传漂变的影响很大。然而，高基因流补偿了遗传漂变。种群内和种群间的遗传结构反映了在其他自交蜗牛物种中观察到的情况，依赖于高自交率、低有效种群规模、环境随机性和高基因流。有效种群大小的所有估计值均低于 7，表明遗传漂变的影响很大。然而，高基因流补偿了遗传漂变。种群内和种群间的遗传结构反映了在其他自交蜗牛物种中观察到的情况，依赖于高自交率、低有效种群规模、环境随机性和高基因流。