Betto-Colliard C, Sermier R, Litvinchuk S, Perrin N, Stöck M
Department of Ecology and Evolution, Biophore Building University of Lausanne, Lausanne, Switzerland.
Institute of Cytology, Russian Academy of Sciences, St Petersburg, Russia.
Heredity (Edinb). 2015 Mar;114(3):300-8. doi: 10.1038/hdy.2014.100. Epub 2014 Nov 5.
Polyploidization, which is expected to trigger major genomic reorganizations, occurs much less commonly in animals than in plants, possibly because of constraints imposed by sex-determination systems. We investigated the origins and consequences of allopolyploidization in Palearctic green toads (Bufo viridis subgroup) from Central Asia, with three ploidy levels and different modes of genome transmission (sexual versus clonal), to (i) establish a topology for the reticulate phylogeny in a species-rich radiation involving several closely related lineages and (ii) explore processes of genomic reorganization that may follow polyploidization. Sibship analyses based on 30 cross-amplifying microsatellite markers substantiated the maternal origins and revealed the paternal origins and relationships of subgenomes in allopolyploids. Analyses of the synteny of linkage groups identified three markers affected by translocation events, which occurred only within the paternally inherited subgenomes of allopolyploid toads and exclusively affected the linkage group that determines sex in several diploid species of the green toad radiation. Recombination rates did not differ between diploid and polyploid toad species, and were overall much reduced in males, independent of linkage group and ploidy levels. Clonally transmitted subgenomes in allotriploid toads provided support for strong genetic drift, presumably resulting from recombination arrest. The Palearctic green toad radiation seems to offer unique opportunities to investigate the consequences of polyploidization and clonal transmission on the dynamics of genomes in vertebrates.
多倍体化有望引发重大的基因组重组，在动物中发生的频率远低于植物，这可能是由于性别决定系统所施加的限制。我们研究了中亚古北界绿蟾蜍（绿蟾蜍亚组）中异源多倍体化的起源和后果，该亚组具有三个倍性水平和不同的基因组传递模式（有性生殖与克隆生殖），目的是：（i）在一个包含多个密切相关谱系的物种丰富的辐射中建立网状系统发育的拓扑结构；（ii）探索多倍体化之后可能发生的基因组重组过程。基于30个交叉扩增微卫星标记的同胞关系分析证实了异源多倍体的母系起源，并揭示了其亚基因组的父系起源和关系。对连锁群的共线性分析确定了三个受易位事件影响的标记，这些易位事件仅发生在异源多倍体蟾蜍父系遗传的亚基因组内，并且专门影响在绿蟾蜍辐射的几个二倍体物种中决定性别的连锁群。二倍体和多倍体蟾蜍物种之间的重组率没有差异，并且总体上在雄性中大幅降低，与连锁群和倍性水平无关。异源三倍体蟾蜍中通过克隆传递的亚基因组为强烈的遗传漂变提供了支持，推测这是由重组停滞导致的。古北界绿蟾蜍辐射似乎为研究多倍体化和克隆传递对脊椎动物基因组动态的影响提供了独特的机会。
