Apakupakul K, Siddall M E, Burreson E M
Department of Biology, University of Michigan, Ann Arbor, Michigan 48109, USA.
Mol Phylogenet Evol. 1999 Aug;12(3):350-9. doi: 10.1006/mpev.1999.0639.
The evolutionary patterns of divergence of seven euhirudinean families were investigated by cladistic analysis of 33 euhirudinean species. Oligochaetes, Acanthobdella peledina, and branchiobdellidans were included as outgroup taxa. Cladistic analysis employed 1.8 kb of nuclear 18S ribosomal DNA and 651 bp of mitochondrial cytochrome c oxidase subunit I in addition to morphological data. The use of two molecular data sets, one nuclear gene and one mitochondrial gene, as well as morphological data combined historical information evolving under a variety of different constraints and therefore was less susceptible to the biases that could confound the use of only one type of data. Results suggest that the nuclear 18S rDNA gene yields a meaningful historical signal for determining higher level relationships. The more rapidly evolving CO-I gene was informative for recent or local areas of the evolutionary hypothesis, such as within-family relationships. Analyses combining all data from the three character sets yielded one most-parsimonious tree. Most of the higher taxa in recent leech systematics were well corroborated in the resulting topology. However, these results suggested paraphyly of the order Rhynchobdellida, which contradicts the presence of a proboscis as a synapomorphy. The medicinal leech family Hirudinidae was polyphyletic because Haemadipsidae and Haemopidae each have a hirudinid ancestor. In addition, all but one of the genera within the family Erpobdellidae must be either abandoned or renamed. Unusual findings included compelling evidence of historical plasticity in bloodfeeding behavior, having been lost at least four times in the course of euhirudinean evolution. Biogeographic patterns supported a New World origin for Arhynchobdellida.
通过对33种真蛭类物种进行分支系统分析，研究了七个真蛭类科的分化进化模式。寡毛纲动物、棘蛭属和蛭蚓目被纳入外类群分类单元。除形态学数据外，分支系统分析还采用了1.8 kb的核18S核糖体DNA和651 bp的线粒体细胞色素c氧化酶亚基I。使用两个分子数据集，一个核基因和一个线粒体基因，以及形态学数据，综合了在各种不同限制条件下进化的历史信息，因此不太容易受到可能混淆仅使用一种数据类型的偏差的影响。结果表明，核18S rDNA基因产生了用于确定更高层次关系的有意义的历史信号。进化较快的CO-I基因对于进化假说的近期或局部区域，如科内关系，具有信息价值。结合来自三个特征集的所有数据进行的分析产生了一棵最简约树。在所得的拓扑结构中，近期水蛭系统学中的大多数高级分类单元得到了很好的证实。然而，这些结果表明吻蛭目的并系性，这与吻作为共同衍征的存在相矛盾。药用蛭科是多系的，因为山蛭科和蛭科都有一个蛭科祖先。此外，蛭科内除一个属外的所有属都必须要么被废弃，要么重新命名。不寻常的发现包括吸血行为历史可塑性的有力证据，在真蛭类进化过程中至少丧失了四次。生物地理模式支持无吻蛭目起源于新大陆。
