Chromosomal evolution in Saccharomyces
Chromosomal evolution in Saccharomyces
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DOI：
10.1038/35013058
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发表时间：
2000-05-25
期刊：
影响因子：
64.8
通讯作者：
Louis, EJ
中科院分区：
文献类型：
--
作者：
Fischer, G;James, SA;Louis, EJ
染色体物种形成模型将染色体重排作为生殖隔离的主要原因(1)。在杂合携带者中，带有相互易位的染色体在减数分裂时错误分离，导致生育能力降低或完全不育。因此，染色体重排起到合子后分离机制的作用。酵母中的生殖隔离是由于合子后的障碍，因为许多物种成功交配，但杂交是不育的(2，3)。相互易位被认为是大规模重排的主要形式，因为10年前(4，5)年前假设复制了整个酵母基因组(4，5)。为了测试酵母中的染色体形态模型，我们表征了酵母中六个密切相关物种的基因组之间的染色体易位。在这里，我们表明，重排发生在亲缘关系密切的物种之间，而较远的物种具有共线的基因组。因此，染色体重排不是酵母物种形成的先决条件，易位的形成速度也不是恒定的。这些重排似乎是Ty元件或其他重复序列之间异位重组的结果。
The chromosomal speciation model invokes chromosomal rearrangements as the primary cause of reproductive isolation(1). In a heterozygous carrier, chromosomes bearing reciprocal translocations mis-segregate at meiosis, resulting in reduced fertility or complete sterility. Thus, chromosomal rearrangements act as a post-zygotic isolating mechanism. Reproductive isolation in yeast is due to post-zygotic barriers, as many species mate successfully but the hybrids are sterile(2,3). Reciprocal translocations are thought to be the main form of large-scale rearrangement since the hypothesized duplication of the whole yeast genome 10(8) years ago(4,5). To test the chromosomal speciation model in yeast, we have characterized chromosomal translocations among the genomes of six closely related species in the Saccharomyces 'sensu stricto' complex(6). Here we show that rearrangements have occurred between closely related species, whereas more distant ones have colinear genomes. Thus, chromosomal rearrangements are not a prerequisite for speciation in yeast and the rate of formation of translocations is not constant. These rearrangements appear to result from ectopic recombination between Ty elements or other repeated sequences.