It is increasingly realized that homoploid hybrid speciation (HHS), which involves no change in chromosome number, is an important mechanism of speciation. HHS will likely increase in frequency as ecological and geographical barriers between species are continuing to be disrupted by human activities. HHS requires the establishment of reproductive isolation between a hybrid and its parents, but the underlying genes and genetic mechanisms remain largely unknown. In this study, we reveal by integrated approaches that reproductive isolation originates in one homoploid hybrid plant species through the inheritance of alternate alleles at genes that determine parental premating isolation. The parent species of this hybrid species are reproductively isolated by differences in flowering time and survivorship on soils containing high concentrations of iron. We found that the hybrid species inherits alleles of parental isolating major genes related to flowering time from one parent and alleles of major genes related to iron tolerance from the other parent. In this way, it became reproductively isolated from one parent by the difference in flowering time and from the other by habitat adaptation (iron tolerance). These findings and further modeling results suggest that HHS may occur relatively easily via the inheritance of alternate parental premating isolating genes and barriers.

人们越来越认识到，不涉及染色体数目变化的同倍体杂交物种形成（HHS）是物种形成的重要机制。由于人类活动继续破坏物种之间的生态和地理障碍，HHS的频率可能会增加。HHS要求在杂种与其亲本之间建立生殖隔离，但基本的基因和遗传机制仍然未知。在这项研究中，我们通过综合方法揭示了生殖分离起源于一种同倍体杂种植物，其通过决定等位基因在决定亲本过早分离的基因上的替代等位基因的遗传来实现。通过在高铁含量的土壤上开花时间和存活率的差异，繁殖分离出该杂种的亲本。我们发现杂种从一个亲本遗传与育种时间相关的亲本分离主要基因的等位基因，而从另一亲本遗传与耐铁性相关的主要基因的等位基因。这样，由于开花时间的不同，它与一个亲本繁殖分离，而由于生境适应（耐铁性）而与另一个亲本分离。这些发现和进一步的建模结果表明，HHS可能通过替代父母亲早产隔离基因和屏障的遗传而相对容易地发生。它通过开花时间的差异与一个亲本繁殖分离，而由于栖息地适应性（耐铁性）而与另一亲本分离。这些发现和进一步的建模结果表明，HHS可能通过替代父母亲早产隔离基因和屏障的遗传而相对容易地发生。它通过开花时间的差异与一个亲本繁殖分离，而由于栖息地适应性（耐铁性）而与另一亲本分离。这些发现和进一步的建模结果表明，HHS可能通过替代父母亲早产隔离基因和屏障的遗传而相对容易地发生。