多倍体物种的适应机制：基于蓍属异源四倍体及其亲本物种的比较研究

杂交-多倍化被认为与植物的适应性演化密切相关，其机制可能是增加了植物基因组的复杂性及其基因表达的变异能力，从而增加了表型可塑性。然而这些理论推测缺乏针对野生物种的实验证据。要验证上述问题，需要一个亲子关系简单清晰、具备扎实群体遗传学和表型多样性研究基础，且各方面实验操作可行的多倍体研究体系。本项目拟利用具备上述条件的东亚蓍属“二倍体-四倍体”亲子代物种体系，利用同质园种植、环境单因子控制栽培实验和人工杂交、多倍化实验，分析若干适合度相关形态性状的变异范围和式样，并对实验材料的基因表达模式进行分析，获得从基因到表型的数据。将这些数据进行多重对比分析（同质种植条件下的物种间；人工构建的杂交多倍化群体与自然群体之间；控制实验的处理组间），检测二倍体和多倍体物种的表型可塑性变异，建立 “基因型-基因表达-表型-适合度”的实验证据链条，检验异源多倍体物种的适应性并探究其机制。

It has long been proposed that polyploids have increased environmental robustness than do their diploid progenitors, potentially leading to evolutionary advantages. But this hypothesis lacks strict empirical evidence. The mechanisms of the polyploid adaptation may be attributed to the increased genetic variation due to genome doubling and recombination which can potentially affect the variability of gene expression patterns, and act subsequently on morphology and physiology traits. Moreover, phenotypic plasticity, per se, as a kind of traits, may also lead to alterations of ecological conditions. To test those hypotheses, there needs a suitable well-studied model polyploid system which has clear progenitor-progeny genealogy and feasibility for laboratory practice. This project attempt to carry out a comparative study using our well-studied diploid-allotetraploid Achillea system in Eastern Asian. We will test a series of morphological traits that are related to plant fitness via common garden experiments and controlled experiments. We will compare phenotypic plasticity of traits and their underlying gene expression, as well as transcriptome data, between differently cultivated populations in the common garden. We will set up a series of artificial hybrid and allotetraploid populations. By comparative analyses from phenotype to gene expression patterns between the artificial and natural polyploid populations, we try to tease apart the influence of hybridization and polyploid, respectively, to the adaptation values of the allopolyploid species. By integrating the multidisciplinary experimental data, we will finally try to answer the question how the genetic and developmental consequences of polyploidy extend to the phenotype and to ecology, that is, to fill the gaps from genes to ecology.