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，以解决多种（4,000个物种）中的几个层次的系统发育关系，主要是热带植物科，以及这些植物与它们在唇形科（薄荷和亲戚）中最近的亲戚之间的关系。 数据的主要来源将是叶绿体和核基因的DNA序列;此外，还将尽可能获取形态信息（包括花粉）和染色体计数。 要完成的工作有四个目标，这些被选择来测试假设的关系，解释形态进化，有助于了解传粉者的关系在菊科的演变，并提供数据，为继续研究分子进化。 目标1是确定与兰科植物最近的现存亲属。 目标2是建立黑红树林属白骨壤的精确系统发育位置。 这些植物已被证明是由以前的工作是密切相关的兰科。 目标3和4是澄清两个亚科，Acantheae和Justiceae内的关系。 分类群取样和数据收集战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提供了重要的新样本，沿着来自非洲和南美洲的同事的材料。 待测序的DNA区域由待解决的关系水平决定：更高水平的工作（目标1和2）需要来自相对缓慢进化的基因座的序列，而兰科（目标3和4）内的工作需要来自进化更快的基因区域的序列。 该物种的丰富性，极端形态多样性，以及几乎世界范围内分布的兰科植物意味着，实现这一项目的目标将有超出系统学的影响。 在系统发育关系的背景下，衍生性状可以从原始性状中分类出来，以澄清形态进化的模式，并提出关于过程的可检验的想法。 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。 古希腊人认为古希腊人起源于冈瓦纳，但古希腊地理学的历史显然比简单的地理分布要复杂得多。所提出的研究将指出易于处理的规模的群体，以解决历史地理问题。 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。 在整个群体中，序列可用的非编码DNA区域不是以时钟样的方式进化的。 添加蛋白质编码基因的序列（本项目期间将完成的工作的一部分）不仅将提供更好的系统发育关系的分辨率，但也将推进形态和分子多样性之间的关系的知识。

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.