Williams H C, Ormerod S J, Bruford M W
Biodiversity and Ecological Processes Group, Main Building, University of Wales Cardiff, Cardiff CF10 3TL, UK.
Mol Phylogenet Evol. 2006 Aug;40(2):370-82. doi: 10.1016/j.ympev.2006.03.004. Epub 2006 May 2.
Genetic studies have highlighted cryptic diversity in many well-known taxa including aquatic insects, with the general implication that there are more species than are currently recognised. Baetis rhodani Pictet are among the most widespread, abundant and ecologically important of all European mayflies (Ephemeroptera), and used widely as biological indicators of stream quality. Traditional taxonomy and systematics have never fully resolved differences among suspected cryptic species in the B. rhodani complex because morphological characters alone do not allow reliable distinction. This is particularly true among larvae, the life-stage used most widely in monitoring. Here, we assess the molecular diversity of this complex in one of the largest such studies of cryptic species in the order Ephemeroptera to date. Phylogenies were constructed using data from the mitochondrial cytochrome oxidase subunit I (COI) gene. Two monophyletic groups were recovered consisting of one major haplogroup and a second clade of 6 smaller but distinct haplogroups. Haplogroup divergence ranged from 0.2-3% (within) to 8-19% (among) with the latter values surpassing maxima typically reported for other insects, and provides strong evidence for cryptic species in the B. rhodani complex. The taxonomic status of these seven haplogroups remains undefined. Their distributions across Western Europe reveal no obvious geographic pattern, suggesting widespread diffusion of genetic lineages since the last glacial maximum. The implications of these findings are far-reaching given the ecological and bioindicator significance of what now appears to be several taxa.
遗传学研究凸显了包括水生昆虫在内的许多知名分类群中存在的隐秘多样性，这普遍意味着实际物种数量比目前公认的要多。红圆尾蜉蝣（Baetis rhodani Pictet）是欧洲所有蜉蝣（蜉蝣目）中分布最广、数量最多且具有重要生态意义的物种之一，并被广泛用作溪流质量的生物指标。传统的分类学和系统学从未完全解决红圆尾蜉蝣复合体中疑似隐秘物种之间的差异，因为仅靠形态特征无法进行可靠区分。在幼虫中尤其如此，幼虫是监测中使用最广泛的生命阶段。在此，我们在迄今为止对蜉蝣目隐秘物种进行的最大规模此类研究之一中，评估了该复合体的分子多样性。利用线粒体细胞色素氧化酶亚基I（COI）基因的数据构建了系统发育树。得到了两个单系类群，一个主要单倍型类群和另一个由6个较小但不同的单倍型类群组成的分支。单倍型类群内的差异范围为0.2 - 3%，类群间的差异为8 - 19%，后者的值超过了通常报道的其他昆虫的最大值，有力地证明了红圆尾蜉蝣复合体中存在隐秘物种。这七个单倍型类群的分类地位仍未确定。它们在西欧的分布没有显示出明显的地理模式，这表明自末次盛冰期以来遗传谱系广泛扩散。鉴于现在看来是几个分类群的生态和生物指示意义，这些发现的影响意义深远。
