Systematics, Phylogeny, and Pollination System Evolution in Callitrichaceae

水下传粉（亲水性）是开花植物中最神秘的传粉系统之一。亲水性要求放弃或修改与干燥、空气开花条件密切相关的一套性状，这代表了花生物学的转变，对花和花粉形态产生了深远的影响。在实现润湿性（花粉在水下释放和捕获）的过程中，机械和生物化学的变化带来了重大的适应性障碍，这在从一种空中授粉系统向另一种空中授粉系统的进化转变中没有遇到过。菲尔布里克博士项目的目标是探索有关水传粉进化的问题，使用卡利特里属作为实验系统。雀花属是进行这些研究的最合适的类群，因为它是被子植物中唯一同时包括空中和水下授粉系统的属。利用形态特征和新的DNA特征进行系统发育分析将有助于了解该属植物的花和花粉特征的变化方向，从而有助于确定适应水下授粉的变化模式。水下授粉是在某些开花植物群中发现的更奇怪的适应性之一。菲尔布里克博士正在用一个明确的系统发育框架研究这一现象，该框架研究了大约50种鸟属植物，其中包括水下和空中授粉系统。可以确定花和花粉特征变化的方向，反过来，这些知识将允许分析负责新花结构的细胞和生化机制。

9307038 Philbrick Underwater pollination (hydrophily) is one of the most enigmatic pollination systems in flowering plants. Hydrophily requires the abandonment or modification of a suite of characters intimately tied to the dry, aerial flowering condition, and represents a shift in floral biology with profound consequences for flower and pollen morphology. The mechanical and biochemical modifications entailed in achieving wettability (underwater release and capture of pollen) raise significant adaptive obstacles not encountered during evolutionary shifts from one aerial pollination system to another. The goals of Dr. Philbrick's project are to probe questions concerning the evolution of water pollination using the genus Callitriche as an experimental system. Callitriche is the most appropriate group to conduct these studies because it is the only genus of angiosperms that includes both aerial and underwater pollination systems. Phylogenetic analysis using morphological and new DNA characters will provide an understanding of the direction of change in floral and pollen features across the species in the genus, and thereby help determine models of change in adaptation to underwater pollination. %%% Underwater pollination is one of the more bizarre adaptations found in certain groups of flowering plants. Dr. Philbrick is studying this phenomenon in an explicit phylogenetic framework for the ca. 50 species of the genus Callitriche that includes both underwater and aerial pollination systems. The direction of change in floral and pollen features can be determined, and in turn this knowledge will allow analysis of cellular and biochemical mechanisms responsible for new floral structure.