Nadler S A
J Nematol. 1995 Dec;27(4):423-32.
The advantages of nucleotide sequence data for studying phylogeny have been shown to include number of potential characters available for comparison, rate independence between molecular and morphological evolution, and utility of molecular data for modeling patterns of nucleotide substitution. Potential pitfalls have also been revealed and include difficulties of inferring positional homology, incongruence between organismal and gene genealogies, and low likelihood of recovering the correct phylogeny given certain patterns in the timing of speciation events. Statistical methods for comparing phylogenetic hypotheses have been used to assess the reliability of alternative trees for ascaridoid nematodes. Based on partial ribosomal RNA sequences, tree topologies inconsistent with monophyly of the Ascaridinae were significantly worse by maximum likelihood inference. The topology of the maximum parsimony tree based on full-length sequences of 18S rRNA and 300 nucleotides of Cytochrome oxidase II for 13 ascaridoid species was generally consistent with traditional taxonomic expectations at lower ranks, but inconsistent with most proposed arrangements at higher taxonomic levels.
用于系统发育研究的核苷酸序列数据的优势已被证明包括可用于比较的潜在特征数量、分子进化与形态进化之间的速率独立性以及分子数据在核苷酸替换模式建模中的效用。也揭示了一些潜在的陷阱，包括推断位置同源性的困难、生物谱系与基因谱系之间的不一致，以及在特定物种形成事件时间模式下恢复正确系统发育的可能性较低。用于比较系统发育假设的统计方法已被用于评估蛔虫类线虫替代树的可靠性。基于部分核糖体RNA序列，通过最大似然推断，与蛔亚科单系性不一致的树形拓扑结构明显较差。基于13种蛔虫类物种的18S rRNA全长序列和细胞色素氧化酶II的300个核苷酸构建的最大简约树的拓扑结构在较低分类级别上通常与传统分类学预期一致，但在较高分类级别上与大多数提议的排列不一致。
