Demographics and phylogeography of hybrid speciation

描述(申请人提供)：拟议研究的目标是更好地了解向日葵属杂交种的人口统计学特征。同一亲本种间杂交形成3个同倍体种。人们认为向日葵的杂交物种形成可能受到创始人事件的促进，但基本上对这些或其他二倍体杂交物种的杂交物种形成的人口统计学一无所知。其具体目标是：1)使用合并方法和遍布整个基因组的多个基因座来估计杂交物种的祖先有效种群规模和种群增长率，以确定它们是否符合创始人事件物种形成模型的预期；2)确定杂交物种和亲本物种之间的渗透水平，并检验导入速率与不同基因组区域的不同选择力和染色体重排相关的假设；3)对亲本物种进行系统地理研究，以验证这样的假设，即引入北美野牛通过增加扩散和在独特栖息地隔离的可能性促进了杂交物种的形成；以及4)对杂交物种进行系统地理研究，以测试范围的扩大。

DESCRIPTION (provided by applicant): The goal of the proposed research is to gain a better understanding of the demographics of hybrid speciation in the sunflower genus Helianthus. Three homoploid species were formed via hybridization between the same two parental species. It is thought that hybrid speciation in Helianthus may have been facilitated by founder events, but essentially nothing is known about the demography of hybrid speciation in these or other diploid hybrid species. The specific aims are to 1) use coalescent methods and many loci spread throughout the genome to estimate ancestral effective population sizes and population growth rates in the hybrid species to determine if they conform to expectations of a founder event speciation model; 2) determine levels of introgression between hybrid and parental species and test the hypotheses that introgression rates are correlated with varying selective forces and chromosomal rearrangements in various genomic regions; 3) perform phylogeographic studies of the parental species to test the hypothesis that the introduction of bison to North America contributed to hybrid speciation by increasing dispersal and the potential for isolation in unique habitats; and 4) perform phylogeographic studies of hybrid species to test for range expansion.