SCCMAR, CIMAR-Laboratdrio Associado, University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal.
Ecology. 2010 Jan;91(1):49-56. doi: 10.1890/09-0050.1.
Isolation by distance (IBD) models are widely used to predict levels of genetic connectivity as a function of Euclidean distance, and although recent studies have used GIS-landscape ecological approaches to improve the predictability of spatial genetic structure, few if any have addressed the effect of habitat continuity on gene flow. Landscape effects on genetic connectivity are even less understood in marine populations, where habitat mapping is particularly challenging. In this study, we model spatial genetic structure of a habitat-structuring species, the giant kelp Macrocystis pyrifera, using highly variable microsatellite markers. GIS mapping was used to characterize habitat continuity and distance between sampling sites along the mainland coast of the Santa Barbara Channel, and their roles as predictors of genetic differentiation were evaluated. Mean dispersal distance (sigma) and effective population size (Ne) were estimated by comparing our IBD slope with those from simulations incorporating habitat continuity and spore dispersal characteristics of the study area. We found an allelic richness of 7-50 alleles/locus, which to our knowledge is the highest reported for macroalgae. The best regression model relating genetic distance to habitat variables included both geographic distance and habitat continuity, which were respectively, positively and negatively related to genetic distance. Our results provide strong support for a dependence of gene flow on both distance and habitat continuity and elucidate the combination of Ne and a that explained genetic differentiation.
基于距离的隔离（IBD）模型被广泛用于预测遗传连通性水平随欧几里得距离的变化，尽管最近的研究已经使用 GIS-景观生态方法来提高空间遗传结构的可预测性，但很少有研究涉及到栖息地连续性对基因流动的影响。在海洋种群中，对遗传连通性的景观影响甚至知之甚少，因为在这些种群中，栖息地绘图尤其具有挑战性。在这项研究中，我们使用高度可变的微卫星标记来模拟一种具有栖息地结构的物种——巨藻 Macrocystis pyrifera 的空间遗传结构。GIS 制图用于描述圣巴巴拉海峡大陆沿岸栖息地连续性和采样点之间的距离，并评估它们作为遗传分化预测因子的作用。通过将我们的 IBD 斜率与包含研究区域栖息地连续性和孢子扩散特征的模拟进行比较，估计了平均扩散距离（sigma）和有效种群大小（Ne）。我们发现等位基因丰富度为 7-50 个等位基因/位点，据我们所知，这是海藻中报道的最高值。与遗传距离相关的最佳回归模型包括地理距离和栖息地连续性，它们分别与遗传距离呈正相关和负相关。我们的研究结果强烈支持基因流动既依赖于距离又依赖于栖息地连续性，并阐明了 Ne 和 a 的组合解释了遗传分化。
