Data from: Large-scale natural disturbance alters genetic population structure of the sailfin molly, Poecilia latipinna

Many inferences about contemporary rates of gene flow are based on the assumption that the observed genetic structure among populations is stable. Recent studies have uncovered several cases in which this assumption is tenuous. Most of those studies have focused on the effects that regular environmental fluctuations can have on genetic structure and gene flow patterns. Occasional catastrophic disturbances could also alter either the distribution of habitat or the spatial distribution of organisms in a way that affects population structure. However, evidence of such effects is sparse in the literature because it is difficult to obtain. Hurricanes, in particular, have the potential to exert dramatic effects on population structure of organisms found on islands or coral reefs or in near shore and coastal habitats. Here we draw on a historic genetic data set and new data to suggest that the genetic structure of sailfin molly (Poecilia latipinna) populations in north Florida was altered dramatically by an unusually large and uncommon type of storm surge associated with Hurricane Dennis in 2005. We compare the spatial pattern of genetic variation in these populations after Hurricane Dennis to the patterns described in an earlier study in this same area. We use comparable genetic data from another region of Florida, collected in the same two periods, to estimate the amount of change expected from typical temporal variation in population structure. The comparative natural history of sailfin mollies in these two regions indicates that the change in population structure produced by the storm surge is not the result of many local extinctions with recolonization from a few refugia but emerged from a pattern of mixing and redistribution.

当前多数针对当代基因流（gene flow）速率的推论，均建立在种群间观测到的遗传结构（genetic structure）保持稳定这一假设之上。近期已有多项研究发现，该假设在诸多案例中并不成立。此类研究大多聚焦于周期性环境波动对遗传结构及基因流模式的影响。偶发的灾难性扰动同样可能改变栖息地分布或生物的空间分布，进而影响种群结构（population structure）。然而，此类效应的相关文献证据较为匮乏，究其原因在于相关数据难以获取。其中，飓风具备对岛屿、珊瑚礁或近岸与沿海生境中生物的种群结构引发剧烈改变的潜力。本研究依托一套历史性遗传数据集与全新遗传数据，提出2005年飓风丹尼斯（Hurricane Dennis）引发的异常大规模且罕见的风暴潮（storm surge），极大改变了佛罗里达州北部帆鳍鳉（sailfin molly, *Poecilia latipinna*）种群的遗传结构。我们将该飓风过后种群的遗传变异空间分布模式，与该区域此前一项研究中报道的分布模式进行了对比。同时，我们利用佛罗里达州另一区域在相同两个时期采集的可比遗传数据，估算了种群结构因典型时间变异而产生的预期变化量。对这两个区域帆鳍鳉的比较自然史研究表明，风暴潮引发的种群结构改变，并非源于多处局部灭绝后由少数避难所种群完成重新定植的过程，而是源自种群混合与重新分布的模式。