Dissertation Research: Phylogenetic Relationships and Pollination of Acridocarpus and Other Old World Malpighiaceae.

0073299Baum、Donoghue和Davis Malighiaceae是一科开花植物，是旧大陆和新大陆热带森林和稀树草原的重要组成部分。尽管果实形态和习性有很大的多样性，但新大陆木兰科是由专门的采油蜜蜂(花序雌蜂)授粉的，并表现出高度保守的花形态。这些收集石油的蜜蜂在东半球并不存在。一些东半球分支，如Acridocarpus，被推定为来自新大陆血统，它们表现出与油蜂授粉和“嗡嗡”授粉有关的特征的组合。这些小组提供了一个机会来研究专业传粉者的损失的后果。这项由研究生Charles Davis在David Baum和Michael Donoghue博士的指导下进行的研究的目标是：(1)利用叶绿体和核DNA序列推断蚂蚁科植物的系统发育关系；(2)推断蝗科植物的系统发育或系谱，以研究与传粉者转移相关的花形态进化模式；以及(3)记录蝗科植物在非洲栖息地的授粉。初步的分子数据表明，东半球的锦鸡儿属属于几个不同的谱系，这表明与蜂鸣授粉相关的形态已经不止一次独立进化。然而，系统发育的几个领域仍然没有得到很好的解决。此外，还需要将几个额外的旧世界谱系添加到现有数据集中。利用核糖体DNA序列对Acridocarpus进行分析，发现了两个主要分支，一个包括马达加斯加和新喀里多尼亚特有的物种，另一个由分布在非洲各地的物种组成。在马达加斯加和新喀里多尼亚的物种中似乎完全没有油腺，但在一些非洲物种中出现了油腺。非洲的田野调查表明，Acridocarpus的物种是由大的木蜂授粉的，蜜蜂在花药上嗡嗡作响，花腺产生糖而不是油。利用额外的叶绿体DNA序列以及核光敏色素基因序列来解决马兜铃科的系统发育问题，将有助于阐明东半球物种的起源和关系。进一步的系统发育工作将使人们能够评估具有相似形态的旧大陆物种是否独立进化，以及这种花卉进化是否与采油传粉者的丧失有关。这项研究将阐明授粉系统转变后形态变化的模式和机制。

0073299Baum, Donoghue, and Davis Malpighiaceae are a family of flowering plants that are an important element of forests and savannas in the Old and New World tropics. New World Malpighiaceae are pollinated by specialized oil-collecting bees (anthophorid females) and exhibit a highly conserved floral morphology despite tremendous diversity in fruit morphology and habit. These oil-collecting bees are absent from the Old World. Some Old World clades, like Acridocarpus, are presumed to be derived from New World lineages and they exhibit a combination of features associated with oil-bee pollination and with "buzz" pollination. These groups provide an opportunity to examine the consequences of the loss of specialized pollinators. The goals of this study by graduate student Charles Davis, under the direction of Drs. David Baum and Michael Donoghue, are (1) to infer the phylogenetic relationships within Malpighiaceae using chloroplast and nuclear DNA sequences, (2) to infer the phylogeny or genealogy of Acridocarpus species in order to examine patterns of floral morphological evolution associated with pollinator shifts, and (3) to document the pollination of Acridocarpus in African habitats. Preliminary molecular data indicate that Old World genera of Malpighiaceae belong to several separate lineages, suggesting that morphologies associated with buzz pollination have evolved more than once independently. However, several areas of the phylogeny remain poorly resolved. Furthermore, several additional Old World lineages need to be added to existing datasets. Analyses of Acridocarpus using ribosomal DNA sequences reveal two major clades, one including species endemic to Madagascar and New Caledonia and the other consisting of species distributed across Africa. Oil glands appear to be entirely absent in species from Madagascar and New Caledonia, but appear in some African species. Fieldwork in Africa indicates that species of Acridocarpus are pollinated by large xylocopine bees that buzz the anthers, and the floral glands produce sugars rather than oils. Resolving the phylogeny of Malpighiaceae with additional chloroplast DNA sequences, along with sequences of a nuclear phytochrome gene, will clarify the origin and relationships of the Old World species. Further phylogenetic work will allow an evaluation of whether Old World species with similar morphologies have evolved independently, and whether such floral evolution is associated with the loss of oil-collecting pollinators. This study will shed light on the patterns and mechanisms of morphological change following a shift in pollination system.