Hedin Marshal C
Department of Biology, Washington University, Saint Louis, Missouri, 63130-4899.
Evolution. 1997 Dec;51(6):1929-1945. doi: 10.1111/j.1558-5646.1997.tb05115.x.
This paper summarizes the results of an initial effort to reconstruct the speciational history of cave spiders (Nesticus) from the southern Appalachian Mountains of eastern North America. The Appalachian Nesticus fauna includes a large series of about 30 species distributed across islandlike cave and montane habitats. Many of the species are geographically restricted; all of the species are found in allopatry. Observed patterns of morphological variation and biogeographic evidence suggest that species diversification in this lineage may have occurred recently, perhaps in response to Pleistocene climatic fluctuations. To address questions about the spatial and temporal dynamics of Nesticus speciation, while accounting for potential phylogenetic difficulties, I have gathered nuclear and mitochondrial DNA sequences for a sample of individuals from 81 populations representing 28 Nesticus species. Analyses of these data indicate that considerable genetic divergence exists within and among currently recognized morphological species. Consistent with relatively deep species divergences, most of which likely predate the Pleistocene, is a prevailing pattern of phylogenetic concordance between taxonomic species and monophyletic gene tree lineages. The few deviations from monophyly detected can be tentatively attributed to a peripatric mode of speciation. Although species limits as inferred by the molecular data are generally concordant with patterns of morphological continuity and discontinuity in genitalia, there is evidence to suggest that cryptic phylogenetic lineages exist within some morphologically continuous units. This observation, in combination with the general depth of species lineages, makes any argument about rapid evolution in Nesticus genitalic characteristics unnecessary.
本文总结了一项初步研究的结果，该研究旨在重建北美东部阿巴拉契亚山脉南部洞穴蜘蛛（内斯蛛属）的物种形成历史。阿巴拉契亚内斯蛛动物群包括约30个物种，分布在岛屿状洞穴和山地栖息地。许多物种在地理上受到限制；所有物种都分布在异域。观察到的形态变异模式和生物地理证据表明，该谱系中的物种多样化可能最近才发生，也许是对更新世气候波动的响应。为了解决关于内斯蛛物种形成的空间和时间动态问题，同时考虑到潜在的系统发育困难，我收集了来自代表28个内斯蛛物种的81个种群的个体样本的核DNA和线粒体DNA序列。对这些数据的分析表明，目前公认的形态物种内部和之间存在相当大的遗传差异。与相对较深的物种分化一致，其中大多数可能早于更新世，分类物种和单系基因树谱系之间存在系统发育一致性的普遍模式。检测到的少数与单系性的偏差可以暂时归因于边域物种形成模式。尽管分子数据推断的物种界限通常与生殖器形态连续性和不连续性模式一致，但有证据表明，在一些形态连续的单元中存在隐秘的系统发育谱系。这一观察结果，结合物种谱系的总体深度，使得关于内斯蛛生殖器特征快速进化的任何论点都没有必要。
