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）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。近期在苏格兰本土发现了一种新的多倍体杂种（异源多倍体，allopolyploid）物种——外来沟酸浆（Mimulus peregrinus），该物种形成于过去140年内，其存在已通过染色体计数得到验证。本研究通过对1200个基因区域开展靶向高深度测序，证实该新物种的亲本来源于罗伯茨沟酸浆（M. x robertsii）——一种由两种已在英国归化并广泛分布的外来物种斑点沟酸浆（M. guttatus）与黄色沟酸浆（M. luteus）杂交形成的不育三倍体杂种。此外，本研究还在奥克尼群岛发现了一个新的外来沟酸浆种群，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罗伯茨沟酸浆种群的基因组复制事件。本研究数据提示，在演化中的外来沟酸浆基因组中，部分等位基因（allele）可能已发生丢失。本次发现的生态模式属沟酸浆属（Mimulus）新物种通过异源多倍化（allopolyploidisation）形成，其新近起源为探究自然演化谱系中杂交与基因组复制的早期阶段提供了绝佳的研究契机。