Darling J A, Reitzel A M, Finnerty J R
Department of Biology, Boston University, 5 Cummington Street, Boston, MA 02215, USA.
Mol Ecol. 2004 Oct;13(10):2969-81. doi: 10.1111/j.1365-294X.2004.02313.x.
Nematostella vectensis is an infaunal anemone occurring in salt marshes, lagoons and other estuarine habitats in North America and the United Kingdom. Although it is considered rare and receives protection in England, it is widely distributed and abundant in the United States, particularly along the Atlantic coast. Recent studies suggest that both anthropogenic dispersal and reproductive plasticity may significantly influence the genetic structure of N. vectensis populations. Amplified fragment length polymorphism (AFLP) fingerprinting of individuals from nine populations in the northeastern United States indicates that stable populations are maintained by both asexual and sexual reproduction; in some cases asexually reproducing lineages exist within sexually reproducing populations. F statistics reveal extraordinarily high degrees of genetic differentiation between populations, even those separated by very short distances (less than 100 m). Genetic distances show little to no correlation with geographical distances, consistent with a role for sporadic, geographically discontinuous dispersal coupled with limited gene flow. No single genotype was found at more than one site, despite apparent homogeneity of habitat. In contrast with reported genotypic distributions for Nematostella in the United Kingdom, where a single clonal genotype dominates at multiple sites through southern England, our data thus fail to support the hypothesis of a general-purpose genotype in the northeastern United States. However, they are consistent with important roles for reproductive plasticity, sporadic introductions and complex local population dynamics in determining the global and regional distribution of this species.
星状海葵（Nematostella vectensis）是一种生活在北美和英国盐沼、泻湖及其他河口栖息地的底栖海葵。尽管它在英国被视为稀有物种并受到保护，但在美国分布广泛且数量众多，尤其是在大西洋沿岸。最近的研究表明，人为扩散和生殖可塑性都可能对星状海葵种群的遗传结构产生重大影响。对美国东北部九个种群个体的扩增片段长度多态性（AFLP）指纹分析表明，稳定的种群通过无性繁殖和有性繁殖得以维持；在某些情况下，有性繁殖种群中存在无性繁殖谱系。F统计量显示种群间存在极高程度的遗传分化，即使是那些距离非常近（不到100米）的种群。遗传距离与地理距离几乎没有相关性，这与零星的、地理上不连续的扩散以及有限的基因流所起的作用一致。尽管栖息地看似同质，但在多个地点未发现单一基因型。与英国报道的星状海葵基因型分布情况相反，在英国，单一克隆基因型在英格兰南部的多个地点占主导地位，因此我们的数据未能支持美国东北部存在通用基因型的假设。然而，它们与生殖可塑性、零星引入以及复杂的当地种群动态在决定该物种的全球和区域分布中所起的重要作用是一致的。
