Cladistic Analyses of Viburnum Based on Molecular Characters

亚利桑那大学的Michael Donoghue博士最初与威斯康星大学的同事Kenneth Sytsma博士合作，计划研究开花植物Viburnum属内部的进化关系以及与其他类群的关系，强调从叶绿体DNA获得的特征。叶绿体基因组将被一组限制酶消化，每一种限制酶在特定的位置裂解分子，并确定这些位置在分子上的确切位置。通过比较物种间核苷酸位置的相似性和差异性，可以确定区分类群的突变的进化模式。在评估属和科之间更远的亲缘关系时，将获得叶绿体基因的完整核苷酸序列，并使用计算机辅助方法进行比较。从分子数据得到的系统发育将与以前基于形态特征获得的树进行比较，并将评估一致性的性质和程度。分子数据可能会解决仅基于形态的含糊不清的关系。此外，已解析的系统发育树将为研究感兴趣的特定形态特征的进化提供一个框架。在水果特征方面，这一点尤其有可能，因为多诺霍博士最近对这些特征进行了详细的研究，并获得了这些特征的发育数据。利用系统发育信息分析发育变化将有助于对生物体形式和功能进化的新兴分析。

Dr. Michael Donoghue of the University of Arizona, working initially with colleague Dr. Kenneth Sytsma at University of Wisconsin, plans to study evolutionary relationships within the flowering plant genus Viburnum and relationships to other groups, emphasizing characters obtained from chloroplast DNA. The chloroplast genome will be digested with a battery of restriction enzymes, each of which cleaves the molecule at specific sites, and the exact position of these sites on the molecule will be determined. Comparison of nucleotide site similarities and differences among the species will allow determination of the evolutionary pattern of mutations separating taxa. In assessing more distant relationships, between genera and families, complete nucleotide sequences of chloroplast genes will be obtained and compared, using computer-aided methods. Phylogenies derived from molecular data will be compared to trees obtained previously based on morphological characteristics, and the nature and extent of congruence will be evaluated. Molecular data are likely to resolve relationships that remain equivocal based on morphology alone. Further, resolved phylogenetic trees will provide a framework for study of the evolution of particular morphological traits of interest. This will be especially vaulable in the case of fruit characters, because these have recently been studied in detail by Dr. Donoghue and developmental data are available for these. The use of phylogenetic information to analyze developmental changes will contribute to emerging analyses of the evolution of form and function in organisms.