Genome-wide sequence-based genotyping supports a nonhybrid origin of Castanea alabamensis

The genus Castanea in North America contains multiple tree and shrub taxa of conservation concern. The two species within the group, American chestnut (Castanea dentata) and chinquapin (C. pumila sensu lato), display remarkable morphological diversity across their distributions in the eastern United States and southern Ontario. Previous investigators have hypothesized that hybridization between C. dentata and C. pumila has played an important role in generating morphological variation in wild populations. A putative hybrid taxon, Castanea alabamensis, was identified in northern Alabama in the early 20th century; however, the question of its hybridity has been unresolved. We tested the hypothesized hybrid origin of C. alabamensis using genome-wide sequence-based genotyping of C. alabamensis, all currently recognized North American Castanea taxa, and two Asian Castanea species at >100,000 single-nucleotide polymorphism (SNP) loci. With these data, we generated a high-resolution phyloge...

北美洲栗属（Castanea）包含多个亟待保育关注的乔木与灌木类群。该类群下辖两个物种——美洲栗（Castanea dentata）与广义锥栗（C. pumila sensu lato），在美国东部及安大略省南部的自然分布范围内展现出显著的形态多样性。此前已有研究者提出假说，认为美洲栗与广义锥栗之间的杂交事件，在野生种群的形态变异产生过程中发挥了重要作用。20世纪早期，研究者在阿拉巴马州北部发现了一个疑似杂交类群——阿拉巴马栗（Castanea alabamensis），但该类群是否为真正的杂交类群这一问题始终未有定论。本研究针对覆盖超过10万个单核苷酸多态性（single-nucleotide polymorphism, SNP）位点的基因组序列，对阿拉巴马栗、目前所有已被正式认可的北美栗属类群以及两个亚洲栗属物种开展了全基因组序列分型，以此验证阿拉巴马栗的杂交起源假说。基于上述实验数据，我们构建了高分辨率的系统地理学...