基于共显性遗传标记的同源多倍体进化生态学分析方法的研究

Polyploids are cells or organisms that have a genome with more than two sets of chromosomes. Because of their importance for speciation, and evolution in general, polyploids are often used as model systems for studies in evolutionary ecology. In such studies using co-dominant genetic markers, due to ambiguous genotype and double reduction in autopolyploids, it is difficult to accurately genotype individuals and to construct mathematical models based on the resulting data. There are thus few analytical methods for the study of autopolyploids, which clearly impedes the use of these important organisms for use in evolutionary ecology research. Additionally, null alleles are prevalent in microsatellites, and will further influence the results. We plan to construct a novel meiosis model, derive the genotypic frequencies at equilibrium, and develop analytical methods based on co-dominant markers for autopolyploids. These new methods will enable the accurate quantification of genetic diversity, genetic distance, genetic structure, population history and relatedness of polyploids, and will solve the existing problems of ambiguous genotype, double reduction and null alleles in using autopolyploids as model organisms. The accuracy of the mathematical model and analytical methods will be assessed by computer simulations and empirical microsatellite data obtained from willow herb (Chamerion angustifolium). A new software package enabling other researchers to use the new methods will be made available. This study will provide a theoretical basis and new analytical methods to further the study of autopolyploids in evolutionary ecology and molecular ecology research.

多倍体指基因组包含两个以上染色体组的细胞或有机体，他们在物种形成和进化方面具有重要意义，是进化生态学研究的热点。使用共显性遗传标记进行进化生态学研究时，由于同源多倍体的歧义基因型和双减数，基因分型和数据建模存在困难，因此分析共显性遗传数据的方法匮乏，制约了同源多倍体进化生态研究的发展。此外，常用的微卫星标记中往往存在无效等位基因，影响了结果的准确性。本课题拟通过建立新的同源多倍体的减数分裂模型，推导平衡状态下的基因型频率，开发适用于同源多倍体共显性遗传标记的分析方法，对同源多倍体进行遗传多样性、遗传距离、遗传结构、种群历史、亲缘系数等分析，解决歧义基因型、双减数以及无效等位基因三方面的问题。通过计算机模拟种群和同源多倍体物种柳兰的微卫星分型数据验证模型的有效性，测试所开发的方法，并编写相应的软件，为同源多倍体进化生态学与分子生态学研究提供理论基础和分析工具。

使用共显性遗传标记进行进化生态学研究时，由于同源多倍体的歧义基因型和双减数，基因分型和数据建模存在困难，因此分析共显性遗传数据的方法匮乏，制约了同源多倍体进化生态研究的发展。通过该项目的实施，我们建立了新的同源多倍体的减数分裂模型，推导了平衡状态下的基因型频率，开发了适用于同源多倍体共显性遗传标记的分析方法。这些方法可以对同源多倍体进行遗传多样性、遗传距离、遗传结构、种群历史、亲缘系数等分析，解决了歧义基因型、双减数以及无效等位基因三方面的问题。新模型、新方法的有效性通过计算机模拟种群和真实数据进行了验证。本研究为多倍体的进化生态学研究提供了理论基础和分析工具，还开发了polygene软件，方便其他研究人员使用。

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