Dissertation Research: Systematics of Palm Subtribe Oncospermatinae

[902082] doyle和Lewis在整个有记载的历史中，棕榈科一直被认为是一个独特的植物群，但在大约200个属之间的分类和系统发育关系仍然不清楚，是世界范围内一小群专家继续研究的主题。在包含areeae， Cocoeae， Geonomae和Hyophorbeae的谱系中，要辨别112个属之间的关系尤其困难。研究生卡尔·刘易斯（Carl Lewis）在康奈尔大学（Cornell University）杰夫·多伊尔（Jeff Doyle）博士的指导下，与其他研究这一谱系部分的研究人员合作，正在进行一项关于蛇尾亚族的系统发育研究。蛇尾亚族由8个属组成，估计有12个物种，分布在印度洋的岛屿和邻近的陆地上。形态学数据和DNA序列将用于解决亚部落内部的关系，并评估该群体的不同生物地理学假设。亚部落的系统发育位置也将被确定，并且这些发现将被整合到整个谱系内关系的新兴假设中。从植物标本馆标本和田间活棕榈树的形态观察中收集到的数据支持了Oncospermatinae亚部落是一个自然谱系的假设。序列数据是从叶绿体基因组中两个不同的DNA区域获得的，这些区域通常用于低分类水平的系统发育研究。不幸的是，这些区域的变化不足以提供棕榈属之间关系的信息。为了寻找更适合本研究的DNA数据，研究人员开发了引物，用于扩增和测序编码苹果酸合成酶（EC 4.1.3.2）的核基因的大内含子，这在以前的系统发育研究中从未使用过。初步数据表明，苹果酸合成酶内含子是棕榈系统发育信息的良好来源，具有足够的核苷酸替换以区分属。一个更集中的调查将对重要的属，包括五个或更多的物种，分布在东南亚沿海和岛屿的广阔地区进行，目标是一个全面的分类专著。

9902082Doyle and Lewis The palm family has been recognized as a distinct group of plants throughout recorded history, but taxonomic and phylogenetic relationships among the ca. 200 genera are still unclear and are the subject of continuing study by a small group of specialists worldwide. It has been particularly difficult to discern reationships among the 112 genera within the lineage containing tribes Areceae, Cocoeae, Geonomae, and Hyophorbeae. In collaboration with other researchers working on portions of this lineage, graduate student Carl Lewis, under the supervision of Dr. Jeff Doyle at Cornell University, is conducting a phylogenetic study of Areceae subtribe Oncospermatinae, a group of eight genera comprising an estimated 12 species distributed on islands and neighboring landmasses of the Indian Ocean. Morphological data and DNA sequences will be used to resolve relationships within the subtribe, and to evaluate different biogeographic hypotheses for the group. The phylogenetic position of subtribe Oncospermatinae will also be determined, and the findings will be integrated into emerging hypotheses of relationships within the entire lineage. Morphological observations were collected from herbarium specimens and from living palms in the field, and these data support the hypothesis that subtribe Oncospermatinae is a natural lineage. Sequence data were obtained from two different DNA regions within the chloroplast genome that are commonly used in phylogenetic research at low taxonomic levels. Unfortunately, these regions are not variable enough to provide information about relationships between palm genera. In a search for DNA data more suitable for this study, the investigators have developed primers for amplifying and sequencing a large intron of the nuclear gene encoding malate synthase (EC 4.1.3.2), which has not been used previously in phylogenetic research. Preliminary data show the malate synthase intron to be a good source of phylogenetic information in palms, with sufficient nucleotide substitutions to discriminate among genera. A more focused investigation will be conducted on the important genus Oncosperma, which contains five or more species occurring over a broad region of coastal and insular southeast Asia, with one goal being a comprehensive taxonomic monograph of the group.