Data from: Origin and genome evolution of polyploid green toads in Central Asia: evidence from microsatellite markers

Polyploidization, which is expected to trigger major genomic reorganizations, occurs much less commonly in animals than in plants, possibly due to 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), in order 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 paternall y 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.

多倍化（polyploidization）被认为会引发大规模基因组重排，其在动物中的发生频率远低于植物，这可能受限于性别决定系统（sex-determination systems）施加的演化约束。我们以中亚地区的古北界绿蟾蜍（Bufo viridis物种复合体）为研究对象，调查其中异源多倍化（allopolyploidization）的起源与演化后果，该类群存在三种倍性水平以及不同的基因组传递模式（有性与无性繁殖），旨在实现两大研究目标：① 解析包含多个近缘支系的物种辐射演化类群的网状系统发育拓扑结构；② 探索多倍化事件后可能发生的基因组重排过程。基于30个跨物种扩增的微卫星标记（microsatellite markers）开展的家系分析，证实了异源多倍体（allopolyploid）的母系起源，并揭示了其亚基因组的父系起源与演化关系。对连锁群（linkage groups）共线性（synteny）的分析发现，3个标记发生了易位事件（translocation events）：这类易位仅发生在异源多倍蟾蜍的父系遗传亚基因组中，且仅涉及在绿蟾蜍辐射演化类群的多个二倍体物种中与性别决定相关的连锁群。重组率（recombination rates）在二倍体与多倍体蟾蜍物种间并无显著差异，且整体上雄性的重组率大幅降低，这一现象不受连锁群类型与倍性水平的影响。异源三倍体蟾蜍中无性传递的亚基因组为强烈的遗传漂变（genetic drift）提供了实验支持，该现象推测由重组阻滞（recombination arrest）所致。古北界绿蟾蜍辐射演化类群似乎为研究脊椎动物中多倍化与无性基因组传递对基因组动态的影响提供了独特的研究模型。