DISSERTATION RESEARCH: Untangling the Evolutionary History of the Verbena Complex (Verbenaceae): Hybridization, Introgression, and Polyploidization

杂交、基因渗入（基因通过杂交从一个物种转移到另一个物种）和多倍体化（染色体加倍）是植物物种形成和进化中的重要现象。一个清晰的描述物种关系的谱系树是理解这些现象的基础，但构建起来却极具挑战性。这项研究有两个目的。首先是制定解决这种谱系树的策略。第二个是使用这些方法来解开马鞭草复合体的进化史，马鞭草复合体是一个以杂交、渗入和多倍体化普遍存在为特征的群体。通过比较叶绿体和细胞核基因组中四个独立DNA区域的序列，将构建谱系树来推断它们之间的关系。此外，数以百计的转座因子（sin和MITEs），可以在染色体上从一个位置移动到另一个位置的遗传因子，将被识别并用于追踪宿主生物的进化史。预期的结果包括一个很好的解决马鞭草复合体的进化树，这将被纳入与阿根廷达尔文研究所植物学家合作的最新分类处理。利用转座因子追踪植物的进化历史是植物进化研究中的一个新应用，可能对植物进化研究产生重大影响。这项研究的结果将在年度科学会议上发表，并提交给同行评议的期刊发表。

Hybridization, introgression (movement of genes from one species into anothervia hybridization), and polyploidization (chromosome doubling) are importantphenomena in plant speciation and evolution. A well-resolved genealogical tree,depicting the species relationships, is fundamental to understand these phenomena, butcan be extremely challenging to construct. This research has two aims. The first is todevelop strategies for resolving such genealogical trees. The second is to use thesemethods to untangle the evolutionary history of the Verbena complex, a groupcharacterized by the prevalence of hybridization, introgression, and polyploidization. Bythe comparing sequences of four independent DNA regions from the chloroplast andnuclear genomes, genealogical trees will be constructed to infer relationships. Inaddition, hundreds of transposable elements (SINEs and MITEs), genetic elements thatcan move from one location to another on chromosomes, will be identified and used totrace the evolutionary history of the organisms that host them.Anticipated outcomes include a well-resolved evolutionary tree of the Verbenacomplex, which will be incorporated into an updated taxonomic treatment incollaboration with botanists at the Instituto Darwinion, Argentina. Using transposableelements to trace evolutionary histories is a novel application to plant evolutionarystudies and may have great impact on such studies. Results from this research will bepresented at annual scientific meetings and submitted to peer-reviewed journals forpublication.