Data from: Speciation by genome duplication: repeated origins and genomic composition of the recently formed allopolyploid species Mimulus peregrinus

Whole genome duplication (polyploidisation) is a mechanism of “instantaneous” species formation that has played a major role in the evolutionary history of plants. Much of what we know about the early evolution of polyploids is based upon studies of a handful of recently formed species. A new polyploid hybrid (allopolyploid) species Mimulus peregrinus, formed within the last 140 years, was recently discovered on the Scottish mainland and corroborated by chromosome counts. Here, using targeted, high-depth sequencing of 1200 genic regions, we confirm the parental origins of this new species from M. x robertsii, a sterile triploid hybrid between the two introduced species M. guttatus and M. luteus that are naturalised and widespread in the United Kingdom. We also report a new population of M. peregrinus on the Orkney Islands and demonstrate that populations on the Scottish mainland and Orkney Islands arose independently via genome duplication from local populations of M. x robertsii. Our data raise the possibility that some alleles are already being lost in the evolving M. peregrinus genomes. The recent origins of a new species of the ecological model genus Mimulus via allopolyploidisation provide a powerful opportunity to explore the early stages of hybridisation and genome duplication in naturally evolved lineages.

全基因组复制（polyploidisation，多倍体化）是一种‘瞬时’物种形成机制，在植物演化历史中发挥了核心作用。目前学界对多倍体早期演化的认知，大多基于对少数新近形成物种的研究。一种形成于距今140年内的新多倍体杂交物种——异源多倍体（allopolyploid）沟酸浆属新种*Mimulus peregrinus*，近期在苏格兰本土被发现，并经染色体计数验证。本研究通过对1200个基因区域开展靶向高深度测序，证实该新种的亲本起源于*M. x robertsii*——一种由两种外来物种*M. guttatus*和*M. luteus*杂交形成的不育三倍体杂种，这两个外来物种目前已在英国归化并广泛分布。本研究还在奥克尼群岛发现了*M. peregrinus*的一个新种群，并证实苏格兰本土与奥克尼群岛的种群均独立起源于当地*M. x robertsii*种群的基因组复制事件。我们的数据表明，在*M. peregrinus*的演化基因组中，部分等位基因已存在丢失的潜在可能。作为生态模式属沟酸浆属（Mimulus）的新物种，其通过异源多倍体化形成的新近起源，为探究自然演化谱系中杂交与全基因组复制的早期阶段提供了绝佳的研究契机。