Selfish DNA and breeding system in flowering plants
Selfish DNA and breeding system in flowering plants
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DOI：
10.1098/rspb.1998.0275
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发表时间：
1998-01-22
影响因子：
4.7
通讯作者：
Trivers, R
中科院分区：
文献类型：
--
作者：
Burt, A;Trivers, R
在许多物种中，一些个体携带一条或多条 B 染色体：额外的或多余的染色体，不属于正常补体的一部分。在大多数经过充分研究的案例中，B 会降低其载体的适应性，并且仅由于类似于减数分裂驱动的积累机制而在群体中持续存在。有人提出，这种基因组寄生虫预计只会在异型杂交的有性物种中持续存在，在这些物种中，未受感染的后代可以不断地重新感染；在近交或无性物种中，所有选择都发生在血统之间，基因组寄生虫要么消失，要么必须进化成共生体或互利共生体。在这里，我们提出了一个简单的群体遗传模型，研究了异交率对 B 染色体频率的影响，发现异交促进了寄生 B 染色体的传播，但抑制了互利共生体的传播。从有关英国植物育种系统和 B 染色体的文献中汇编的数据表明，B 染色体更有可能来自专性异交物种，而不是近交物种。这些结果支持了大多数 B 染色体是寄生性的观点，并且育种系统在自私基因的生物学中发挥着核心作用。
In many species, some individuals carry one or more B chromosomes: extra, or supernumerary chromosomes not part of the normal complement. In most well-studied cases, B's lower the fitness of their carrier and persist in populations only because of accumulation mechanisms analogous to meiotic drive. It has been suggested that such genomic parasites are expected to persist only in outcrossed sexual species, in which uninfected lines of descent can be continuously reinfected; in inbred or asexual species, all selection is between lines of descent, and the genomic parasites are either lost or must evolve into commensals or mutualists. Here we present a simple population genetic model of the effect of outcrossing rate on the frequency of B chromosomes, and find that outcrossing facilitates the spread of parasitic B's, but inhibits the spread of mutualists. Data compiled from the literature on breeding system and B chromosomes of British plants indicate that B's are much more likely to be reported from obligately outcrossed species than inbred species. These results support the ideas that most B chromosomes are parasitic, and that breeding systems play a central role in the biology of selfish genes.