Chromosomal Evolution, Genetic Diversity, and Speciation Mechanisms in Polyploid Tragopogon (Asteraceae)

多倍体或全基因组重复是开花植物进化的主要力量，许多开花植物物种都是通过杂交和多倍体的结合过程起源的。染色体变化可能通过多倍体中基因的丢失和重复产生遗传多样性，并可能促进物种形成，但在自然发生的年轻多倍体植物中染色体进化的程度尚不清楚。分子细胞遗传学方法将用于研究向日葵科小角角龙和杂记角龙染色体和基因组的变化。这些物种是最近（近80年）通过亲本物种不同种群的杂交而形成的。此外，这两种多倍体的合成系已经在实验室中生产出来。因此，角蟾提供了一个独特的机会来比较年轻的自然和合成多倍体植物的染色体变异。该项目将研究新多倍体中染色体变异的程度，是否有某些“规则”支配着发生的变化类型，以及这种变异对自然种群的影响。多倍体在开花植物中很常见（一组有30万种或更多的物种）。此外，世界上所有的主要作物和最严重的杂草都是多倍体。因此，描述多倍体形成后不久发生的过程对于了解大多数植物物种的基因组，从而保护植物生物多样性并从中持续受益的能力至关重要。结合DNA序列分析，该项目将在染色体、基因组和遗传水平上为多倍体化过程提供新的见解。

Polyploidy, or whole genome duplication, is a major force in flowering plant evolution, with many flowering plant species having originated through the combined processes of hybridization and polyploidy. Chromosomal changes may generate genetic diversity via loss and duplication of genes in polyploids and may promote speciation, but the extent of chromosomal evolution in young, naturally occurring polyploid plants is unknown. Molecular cytogenetic methods will be used to investigate chromosomal and genomic changes in Tragopogon mirus and T. miscellus of the sunflower family. These species formed recently (in the past 80 years) and repeatedly through hybridization of different populations of the parental species. Furthermore, synthetic lines of both polyploids have been produced in the lab. Tragopogon therefore provides a unique opportunity to compare chromosomal variation in young natural and synthetic polyploid plants. This project will address the extent of chromosomal variation in new polyploids, whether or not certain "rules" govern the types of changes that occur, and the effect of this variation in natural populations. Polyploidy is common in flowering plants (a group of 300,000 or more species). Furthermore, all of the world's major crops and most serious weeds are polyploid. Therefore, characterizing the processes that take place shortly after polyploid formation is crucial for understanding the genomes of most plant species, and thus for our ability to conserve plant biodiversity and sustainably benefit from it. In conjunction with DNA sequence analyses, this project will provide new insight into the process of polyploidization at the chromosomal, genomic, and genetic levels.