Chang Yuhang, Zhao Shengxuan, Xiao Hanwen, Liu Detuan, Huang Yanbo, Wei Yukun, Ma Yongpeng
Yunnan Key Laboratory for Integrative Conservation of Plant Species with Extremely Small Populations, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, China.
University of Chinese Academy of Sciences, Beijing, China.
Front Plant Sci. 2022 Oct 18;13:1010577. doi: 10.3389/fpls.2022.1010577. eCollection 2022.
Natural hybridization plays an important role in speciation; however, we still know little about the mechanisms underlying the early stages of hybrid speciation. Hybrid zones are commonly dominated by Fs, or backcrosses, which impedes further speciation. In the present study, morphological traits and double digest restriction-site associated DNA sequencing (ddRAD-seq) data have been used to confirm natural hybridization between and . , the first case of identification of natural hybridization using combined phenotypic and molecular evidence in the East Asian clade of . We further examined several reproductive barriers in both pre-zygotic and post-zygotic reproductive stages to clarify the causes and consequences of the hybridization pattern. Our results revealed that reproductive isolation between the two species was strong despite the occurrence of hybridization. Interestingly, we found that most of the hybrids were likely to be Fs. This is a very unusual pattern of hybridization, and has rarely been reported before. The prevalence of geitonogamy within these self-compatible hybrids due to short distance foraging by pollinators might explain the origin of this unusual pattern. Fs can self-breed and develop further, therefore, we might be witnessing the early stages of hybrid speciation. Our study provides a new case for understanding the diversification of plants on the Qinghai-Tibet Plateau.
自然杂交在物种形成中起着重要作用；然而，我们对杂交物种形成早期阶段的潜在机制仍然知之甚少。杂交带通常以F1代或回交后代为主，这阻碍了进一步的物种形成。在本研究中，形态特征和双酶切限制性位点关联DNA测序（ddRAD-seq）数据已被用于证实[具体物种]之间的自然杂交。这是在[具体东亚分支]中首次利用表型和分子证据相结合鉴定自然杂交的案例。我们进一步研究了合子前和合子后生殖阶段的几个生殖障碍，以阐明杂交模式的原因和后果。我们的结果表明，尽管发生了杂交，但两个物种之间的生殖隔离仍然很强。有趣的是，我们发现大多数杂种可能是F1代。这是一种非常不寻常的杂交模式，以前很少有报道。由于传粉者近距离觅食，这些自交亲和杂种中同株异花授粉的普遍存在可能解释了这种不寻常模式的起源。F1代可以自交并进一步发育，因此，我们可能正在见证杂交物种形成的早期阶段。我们的研究为理解青藏高原植物的多样化提供了一个新案例。
