Phylogenetic Relationships Among the Cucurbitaceae and Allied Families

[9306913] Swensen葫芦科和海棠科是两个植物科，它们的成员表现出非常不同的形态特征，但它们彼此之间以及与相关类群的系统发育关系尚不清楚。葫芦科因其果实结构的多样性而广受欢迎（比较南瓜、丝瓜、黄瓜和佛手瓜），而秋海棠则表现出花结构和叶形式的多样性。博士的研究。Swensen和Rieseberg计划使用叶绿体和核基因组的DNA基因序列来比较这两个家族的成员和几个假定的亲戚。这些新的分子数据将与用于这些植物分类的传统形态学特征进行比较，以确定一致的区域和不一致的区域。在一致的地方，数据将允许识别可靠的形态特征，用于分类群鉴定和研究性状的进化变化。分歧将突出同源性问题和分子进化速率可能存在的差异。还将研究两个相关的科，datisscaceae和Coriariaceae。这些植物包括与固氮放线根菌共生的植物。这项研究将调查这种联系的演变，并将提供关于为什么它发生在某些群体而不是其他群体的假设。这一信息将被证明对农业上重要植物的固氮共生的诱导是有用的。

9306913 Swensen The Cucurbitaceae and Begoniaceae are two plant families whose members exhibit very distinctive morphological features, yet their phylogenetic relationships to each other and to related groups remain unclear. The cucurbit family is widely appreciated for its diversity of fruit structures (compare pumpkin, luffa, cucumber, chayote) whereas the begonias show a diversity of floral structures and leaf forms. Research by Drs. Swensen and Rieseberg is designed to use DNA gene sequences from the chloroplast and nuclear genomes for comparing members of these two families and several putative relatives. The new molecular data will be compared with traditional morphological characters used in the taxonomy of these plants, in order to determine areas of congruence and areas of disagreement. Where congruent, the data will allow recognition of reliable morphological features for taxon identification and for study of evolutionary change in characters. Disagreements will highlight problems of homology and possible differences in rates of molecular evolution. %%% Two related families, Datiscaceae and Coriariaceae, will also be studied. These include plants with symbiotic associations with nitrogen fixing actinorhizal bacteria. The research will investigate the evolution of this association and will provide hypotheses as to why it occurs in some groups and not in others. This information should prove useful in the induction of nitrogen fixing symbioses in agriculturally important plants.