The evolution of the karyotype and genome size was examined in species of Crepis sensu lato. The phylogenetic relationships, inferred from the plastid and nrITS DNA sequences, were used as a framework to infer the patterns of karyotype evolution. Five different base chromosome numbers (x = 3, 4, 5, 6, and 11) were observed. A phylogenetic analysis of the evolution of the chromosome numbers allowed the inference of x = 6 as the ancestral state and the descending dysploidy as the major direction of the chromosome base number evolution. The derived base chromosome numbers (x = 5, 4, and 3) were found to have originated independently and recurrently in the different lineages of the genus. A few independent events of increases in karyotype asymmetry were inferred to have accompanied the karyotype evolution in Crepis. The genome sizes of 33 Crepis species differed seven-fold and the ancestral genome size was reconstructed to be 1 C = 3.44 pg. Both decreases and increases in the genome size were inferred to have occurred within and between the lineages. The data suggest that, in addition to dysploidy, the amplification/elimination of various repetitive DNAs was likely involved in the genome and taxa differentiation in the genus.

中文翻译：

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降序异常倍体和基因组大小的双向变化伴随着 Crepis（菊科）进化


在Crepis sensu lato 物种中检查了核型和基因组大小的进化。从质体和 nrITS DNA 序列推断出的系统发育关系被用作推断核型进化模式的框架。观察到五个不同的碱基染色体编号（ x = 3、4、5、6 和 11）。对染色体数目进化的系统发育分析允许推断x = 6 作为祖先状态，并且下降的异倍体作为染色体碱基数目进化的主要方向。发现衍生的基本染色体编号（ x = 5、4和3）在该属的不同谱系中独立且循环地起源。据推测，核型不对称性增加的一些独立事件伴随着Crepis 的核型进化。 33 个Crepis物种的基因组大小相差七倍，祖先基因组大小重建为 1 C = 3.44 pg。据推断，基因组大小的减小和增加都发生在谱系内部和谱系之间。数据表明，除了异倍体之外，各种重复DNA的扩增/消除可能与该属的基因组和分类群分化有关。