Data from: Phylogeography of Petrolisthes armatus, an invasive species with low dispersal ability

Theoretically, species with high population structure are likely to expand their range, because marginal populations are free to adapt to local conditions; however, meta-analyses have found a negative relation between structure and invasiveness. The crab Petrolisthes armatus has a wide native range, which has expanded in the last three decades. We sequenced 1718 bp of mitochondrial DNA from native and recently established populations to determine the population structure of the former and the origin of the latter. There was phylogenetic separation between Atlantic and eastern Pacific populations, and between east and west Atlantic ones. Haplotypes on the coast of Florida and newly established populations in Georgia and South Carolina belong to a different clade from those from Yucatán to Brazil, though a few haplotypes are shared. In the Pacific, populations from Colombia and Ecuador are highly divergent from those from Panamá and the Sea of Cortez. In general, populations were separated hundreds to million years ago with little subsequent gene flow. High genetic diversity in the newly established populations shows that they were founded by many individuals. Range expansion appears to have been limited by low dispersal rather than lack of ability of marginal populations to adapt to extreme conditions.

理论上，具备高种群结构（population structure）的物种更易扩张分布范围，因边缘种群可自由适应当地环境；但荟萃分析结果显示，种群结构与入侵性之间呈负相关关系。Petrolisthes armatus（武装瓷蟹）的原生分布范围广泛，且在过去三十年中出现了扩张。本研究对原生种群与新近建立种群的1718 bp线粒体DNA（mitochondrial DNA）进行测序，以解析前者的种群结构，并追溯后者的起源。大西洋种群与东太平洋种群之间，以及大西洋东西部种群之间均存在系统发育分化。佛罗里达沿岸的单倍型（haplotype）以及佐治亚州与南卡罗来纳州的新近建立种群，与尤卡坦至巴西区域的单倍型分属不同的进化枝（clade），尽管二者共享少量单倍型。在太平洋区域，哥伦比亚与厄瓜多尔的种群与巴拿马及科尔特斯海的种群分化程度极高。总体而言，各种群的分化时间距今已有数百年至百万年，后续的基因流（gene flow）极少。新近建立种群的遗传多样性较高，表明其定植来源为多个体群体。该物种的分布范围扩张似乎受限于扩散能力不足，而非边缘种群适应极端环境的能力缺失。