Dissertation Research: Systematics of Palm Subtribe Oncospermatinae

9902082Doyle和Lewis棕榈科在有记录的历史上一直被认为是一个独特的植物类群，但大约200个属之间的分类和系统发育关系仍然不清楚，是世界各地一小群专家继续研究的主题。在包含槟榔亚科、椰亚科、地质亚科和高霍比亚族的谱系中，辨别112个属之间的关系尤其困难。在康奈尔大学杰夫·道尔博士的指导下，研究生卡尔·刘易斯与其他研究人员合作，对槟榔亚族OnCospermatinae进行了系统发育研究。OnCospermatinae是一个由8个属组成的群体，估计有12个物种分布在印度洋的岛屿和邻近大陆上。形态数据和DNA序列将被用来解决亚部落内部的关系，并评估该群体的不同生物地理假说。还将确定人精子亚族的系统发育地位，这些发现将被整合到关于整个谱系内关系的新兴假说中。形态观察来自标本标本和野外活体棕榈树，这些数据支持Oncopermatinae亚族是一个自然谱系的假设。序列数据是从叶绿体基因组中的两个不同的DNA区域获得的，这两个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有关棕榈属之间关系的信息。为了寻找更适合这项研究的DNA数据，研究人员开发了用于扩增和测序编码苹果酸合成酶(EC 4.1.3.2)核基因的一个大内含子的引物，该基因以前从未在系统发育研究中使用过。初步数据表明，苹果酸合成酶内含子是棕榈树系统发育信息的一个很好的来源，有足够的核苷酸替换来区分属间。将对重要的OnCosperma属进行更有重点的调查，该属包含五个或更多物种，分布于东南亚沿海和岛屿的广大地区，一个目标是建立该组的全面分类学专著。

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.