Stockman Amy K, Bond Jason E
East Carolina University, Department of Biology, Howell Science Complex N211, Greenville, NC 27858, USA.
Mol Ecol. 2007 Aug;16(16):3374-92. doi: 10.1111/j.1365-294X.2007.03389.x.
Species exhibiting morphological homogeneity and strong population structuring present challenging taxonomic problems: morphology-based approaches infer few species, whereas genetic approaches often indicate more. Morphologically cryptic, yet genetically divergent species groups require alternative approaches to delimiting species that assess adaptive divergence and ecological interchangeability of lineages. We apply such an approach to Promyrmekiaphila, a small genus (three nominal taxa) of trapdoor spiders endemic to northern California to define cohesion species (lineages that are genetically exchangeable and ecologically interchangeable). Genetic exchangeability is evaluated using standard phylogeographical techniques (e.g. nested clade analysis); ecological interchangeability is assessed using two GIS-based approaches. First, climatic values are extracted from layer data for each locality point and utilized in a principal components analysis followed by MANOVA. Second, niche-based distribution models of genetically divergent lineages are created using a maximum-entropy modelling approach; the amount of overlap among lineages is calculated and evaluated against a probability distribution of null overlap. Lineages that have significant amounts of predicted overlap are considered ecologically interchangeable. Based on a synthetic evaluation of ecological interchangeability, geographical concordance, and morphological differentiation, we conclude that Promyrmekiaphila comprises six cohesion species, five of which are cryptic (i.e. undetectable by conventional means).
基于形态学的方法推断出的物种较少，而遗传学方法往往显示出更多物种。形态学上隐秘但遗传学上有差异的物种群需要采用其他方法来界定物种，这些方法要评估谱系的适应性分化和生态可互换性。我们将这样一种方法应用于Promyrmekiaphila，这是一种分布于加利福尼亚北部的小型螲蟷蛛属（三个命名分类单元），以定义凝聚种（在遗传上可交换且在生态上可互换的谱系）。使用标准的系统地理学技术（如嵌套支系分析）评估遗传可交换性；使用两种基于地理信息系统的方法评估生态可互换性。首先，从每个地点的图层数据中提取气候值，并用于主成分分析，随后进行多变量方差分析。其次，使用最大熵建模方法创建遗传分化谱系的基于生态位的分布模型；计算谱系之间的重叠量，并根据零重叠的概率分布进行评估。具有大量预测重叠的谱系被认为在生态上是可互换的。基于对生态可互换性、地理一致性和形态分化的综合评估，我们得出结论，Promyrmekiaphila包含六个凝聚种，其中五个是隐秘的（即通过传统方法无法检测到）。
