The evolution of genetic systems

我们的实验室研究交配系统修饰因子的进化，更一般地说，研究偏向于自身传播的基因。本研究拟对Leavenworthia属植物的自交不亲和性（SI）的进化和丧失进行研究。本研究将探讨从种群水平到基因序列的交配系统进化，并将重点放在s位点的变异上。在过去的10年里，研究人员在拟南芥属中克隆和测序了这个基因座，取得了相当大的进展。我们将利用这些知识，将SI的进化和丧失的研究扩展到一个生态已被很好地表征的植物群。我们已经在该项目的许多组成部分上取得了重大进展，首先是使用PCR引物靶向s位点的一些保守区域，作为克隆和测序基因的手段。我们的目标包括：(1)确认扩增产物与s位点对应；(2)发展和测试新的和现有的等位基因谱系理论和导致自交亲和的s位点突变动力学；(3)种群大小变化对SI种群配偶可得性和繁殖力的影响；(4) Leavenworthia种自交亲和群体s位点选择性扫描试验；(5)利用古s座多态性数据，协助重建Leavenworthia种交配系统的进化史；(6)对s位点区域有害突变选择的屏蔽试验。总的来说，这项研究将扩展我们对植物自花受精进化的理解。此外，研究人员还计划完成一个项目，研究转座因子（TE）序列进化的早期阶段，并伴随异源TE（来自其他物种的TE）“入侵”新基因组进入酵母的实验群体。这两个项目在概念上是相关的，因为它们都涉及基因的进化，这些基因有能力偏向它们自己的传播，这是我们实验室已经探索了20多年的主题。

Our lab studies the evolution of modifiers of the mating system, and more generally, genes that bias their own transmission. We propose to conduct studies of the evolution and loss of self-incompatibility (SI) in the plant genus Leavenworthia.   This research will investigate mating system evolution from the level of the population on down to the gene sequence, and will focus on variation at the S-locus. Considerable progress has been made in the past 10 years by researchers who have cloned and sequenced this locus in the related genus Arabidopsis. We will capitalize upon this knowledge to extend the study of evolution and loss of SI to a plant group whose ecology has been well characterized.  We have already made significant progress on a number of components of this project, starting with the use of PCR primers that target a number of conserved regions of the S-locus as the means to clone and sequence the gene.  Our goals include: (1) confirmation that amplified products correspond to the S-locus; (2) development and testing of new and existing theory for allele genealogy and the dynamics of mutations at the S-locus that lead to self-compatibility; (3) examination of the effect of population size variation on mate availability and fecundity in SI populations; (4) tests for a selective sweep at the S-locus in self-compatible populations of Leavenworthia species; (5) using ancient S-locus polymorphism data to assist in reconstruction of the evolutionary history of the mating system in Leavenworthia species; (6) tests for the sheltering from selection of deleterious mutations in the S-locus region.  Collectively, this research will extend our understanding of the evolution of self-fertilization in plants.  Also proposed is the completion of a project to investigate the early stages of transposable element (TE) sequence evolution accompanying the "invasion" of a new genome by a heterologous TE (TE from another species) into experimental populations of yeast.  The two projects are conceptually related in that both are concerned with the evolution of genes that have the ability to bias their own transmission, a topic that our lab has explored for more than 20 years.