Molecular Systematics of Ascaridoid Nematodes

核苷酸序列数据将用于评估蛔虫类线虫之间的系统发育关系。然后，这种寄生虫的系统发育将作为检验有关形态特征和生活史属性进化的假说的框架。对核糖体RNA直接测序和对这些数据进行最大简约分析的初步研究表明，核糖体RNA序列为蛔虫类线虫提供了大量的信息特征和可靠的系统发育假说。更具包容性的蛔虫系统发育将有助于检验形态特征和生命周期属性进化的相互竞争的假说。对特征和属性的进化模式的分析将通过应用Farris优化来将这些特征映射到从序列数据推断的物种分支图上。一个独立的系统发育假说，基于对记载的形态特征的分支分析，也将被开发出来。此外，分子和形态数据集将用于组合(和未加权)的系统发育分析。基于形态的和“组合的”系统发育假说对于生活史属性的进化的含义也将通过作图来探索。最后，将识别和检查分子和形态数据集之间的特定区域的一致性和不同之处，并将为每个数据库(形态、分子和组合)独立评估其他研究人员提出的系统发育假说的相对效率。

Nucleotide sequence data will be used to estimate phylogenetic relationships among ascaridoid nematodes. This parasite phylogeny then will serve as a framework for testing hypotheses concerning the evolution of morphological characters and life history attributes. Initial research involving direct sequencing of ribosomal-RNA and maximum parsimony analysis of these data indicates that ribosomal-RNA sequences provide a large number of informative characters and a robust phylogenetic hypothesis for ascaridoid nematodes. A more inclusive phylogeny of ascaridoids will be useful for testing competing hypotheses for the evolution of morphological characters and life cycle attributes. Analysis of evolutionary patterns for characters and attributes will be performed by applying Farris optimization to map these characters on the species cladogram inferred from the sequence data. An independent phylogenetic hypothesis based on cladistic analysis of documented morphological characters will also be developed. In addition, the molecular and morphological data sets will be used for a combined (and unweighted) phylogenetic analysis. The implications of the morphologically based and "combined" phylogenetic hypotheses for the evolution of life history attributes will also be explored by mapping. Finally, specific area of congruence and dissimilarity between the molecular and morphological data sets will be identified and examined, and the relative efficiency of phylogenetic hypotheses proposed by other researchers will be assessed independently for each data base (morphological, molecular, and combined).