Phylogenetics of Acanthaceae: A nested approach to resolving relationships of Acanthaceae and their closest relatives

费城自然科学院的露辛达·麦克达德博士和加州科学院的托马斯·丹尼尔博士正在进行一项合作研究，以解决不同种类（4000种）的系统发育关系，主要是热带植物科的五加科，以及这些植物和它们在薄荷目的近亲（薄荷和近亲）之间的关系。数据的主要来源将是叶绿体和细胞核基因的DNA序列；此外，形态学信息（包括花粉）和染色体计数也将尽可能获得。要完成的工作有四个目标；这些被选择来检验关于关系的假设，解释形态进化，有助于理解棘科传粉者关系的进化，并为继续研究分子进化提供数据。目标1是确定棘科现存的近亲。目标2是建立精确的系统发育位置的黑红树林属Avicennia。这些植物已被先前的工作证明是与棘科密切相关的。目标3和目标4是澄清棘科，棘科和棘科两个亚系之间的关系。分类群取样和数据收集策略将补充现有的和正在进行的项目，马达加斯加的实地工作将提供关键的新样本，以及那里的同事从非洲和南美洲获得的材料。待测序的DNA区域由待解决的关系水平决定：较高水平的工作（目标1和2）需要来自相对缓慢进化的位点的序列，而刺科的工作（目标3和4）需要来自进化更快的基因区域的序列。棘科植物的物种丰富度、极端的形态多样性和几乎世界范围的分布意味着实现该项目的影响将超越系统学。在系统发育关系的背景下，衍生性状可以从原始性状中进行分类，以阐明形态进化的模式，并提出关于过程的可测试的想法。植物作为形态生物与环境相互作用，因此形态学是理解生态和进化过程的关键。例如，通过解释形态进化，为研究传粉者关系的进化奠定了基础。棘科一直被认为起源于冈瓦纳，但很明显，生物地理历史比简单的变异要复杂得多。提出的研究将指向可处理规模的群体，以解决历史生物地理学问题。最后，很明显，在这个群体中存在着令人着迷的分子进化问题。序列可用的非编码DNA区域在整个群体中并没有像时钟一样进化。增加蛋白质编码基因的序列（本项目将要完成的部分工作）不仅可以更好地解决系统发育关系，而且可以促进形态学和分子多样性之间关系的认识。

Dr. Lucinda McDade of the Philadelphia Academy of Natural Sciences and Dr. Thomas Daniel at the California Academy of Sciences are conducting a collaborative study to resolve phylogenetic relationships at several levels within the diverse (4,000 species), largely tropical plant family Acanthaceae and between these plants and their closest relatives in the order Lamiales (mints and relatives). The primary source of data will be DNA sequences from chloroplast and nuclear genes; in addition, morphological information (including pollen) and chromosome counts will also be acquired whenever possible. The work to be accomplished has four goals; these were chosen to test hypotheses regarding relationships, to interpret morphological evolution, to contribute toward understanding the evolution of pollinator relationships in Acanthaceae, and to provide data for continued studies of molecular evolution. Goal 1 is to identify the closest living relatives of Acanthaceae. Goal 2 is to establish the precise phylogenetic placement of the black mangrove genus Avicennia. These plants have been shown by previous work to be closely related to Acanthaceae. Goals 3 and 4 are to clarify relationships within two sublineages of Acanthaceae, Acantheae and Justicieae. Taxon sampling and data gathering strategies will complement existing and on-going projects, with field work in Madagascar providing critical new samples along with material from Africa and South America from colleagues there. Regions of DNA to be sequenced were determined by the level of relationships to be resolved: higher level work (goals 1 and 2) requires sequences from relatively slowly evolving loci, whereas work within Acanthaceae (goals 3 and 4) requires sequences from gene regions that are evolving more rapidly. The species richness, extreme morphological diversity, and nearly worldwide distribution of Acanthaceae mean that achieving the goals of this project will have impact beyond systematics. In the context of phylogenetic relationships, derived characters can be sorted from primitive characters to clarify both the pattern of morphological evolution and suggest testable ideas about process. Plants interact with environments as morphological beings and thus morphology is key to understanding ecological and evolutionary processes. For example, by interpreting morphological evolution, the stage is set for studies of the evolution of pollinator relationships. Acanthaceae have been thought of as Gondwanan in origin, but it is clear that biogeographic history has been much more complicated than simple vicariance. The research proposed will point to groups of tractable size with which to address historical biogeography. Finally, it is clear that there are fascinating problems of molecular evolution in this group. The non-coding DNA regions for which sequences are available are not evolving in a clock-like fashion throughout the group. Adding sequences for protein-coding genes (part of the work to be accomplished during this project) will not only provide better resolution of phylogenetic relationships but will also advance knowledge of the relationship between morphological and molecular diversity.