Background and Aims Niche differentiation is a critical issue in speciation. Although it has a well-known role in adaptive processes of hybrid angiosperms, it is less understood in hybrid ferns. Here we investigate whether an intermediate ecological niche of a fern hybrid is a novel adaptation that provides insights into fern hybrid speciation. Methods Pteris fauriei (Pteridaceae) is a natural hybrid fern, occurring environments between its parent species. The maternal P. minor is found in sunny areas, but the habitat of the paternal P. latipinna is shady. We combined data from morphology, leaf anatomy, and photosynthetic traits to explore adaptation and differentiation, along with measuring the environmental features of their niches. We also performed experiments in a common garden to understand ecological plasticity. Key Results The hybrid P. fauriei is intermediate between the parent species in stomatal density, leaf anatomical features, and photosynthetic characteristics in both natural habitats and a common garden. Interestingly, the maternal P. minor showed significant environmental plasticity and was more similar to the hybrid P. fauriei in the common garden, suggesting that the maternal species experiences stress in its natural habitats but thrives in the environments similar to the hybrid’s. Conclusions Based on the similar niche preferences of the hybrid and parents, we propose hybrid superiority. Our results indicate that the hybrid P. fauriei exhibits greater fitness and can compete with and occupy the initial niches of the maternal P. minor. Consequently, we suggest that the maternal P. minor has experienced a niche shift, elucidating the pattern of niche differentiation in this hybrid group. These findings offer a potential explanation for the frequent occurrence of hybridization in ferns and provide novel insights into fern hybrid speciation, enhancing our understanding of fern diversity.

中文翻译：

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蕨类植物杂交物种形成中的生态位和表型分化，以 Pteris fauriei（凤尾蕨科）为例

背景和目标生态位分化是物种形成的一个关键问题。尽管它在杂交被子植物的适应过程中具有众所周知的作用，但在杂交蕨类植物中人们对其了解较少。在这里，我们研究蕨类杂交的中间生态位是否是一种新颖的适应，为蕨类杂交物种形成提供了见解。方法 Pteris fauriei（凤尾蕨科）是一种天然杂交蕨类植物，出现在其亲本物种之间的环境中。母本 P.minor 生活在阳光充足的地区，而父本 P. latipinna 则栖息在阴凉处。我们结合了形态学、叶子解剖学和光合特征的数据来探索适应性和分化，并测量其生态位的环境特征。我们还在一个普通花园中进行了实验，以了解生态可塑性。主要结果 在自然栖息地和普通花园中，杂交 P. fauriei 的气孔密度、叶片解剖特征和光合特征介于亲本物种之间。有趣的是，母体P.minor表现出显着的环境可塑性，并且与普通花园中的杂交P.fauriei更相似，这表明母体物种在其自然栖息地中经历压力，但在与杂交体相似的环境中茁壮成长。结论基于杂种和亲本相似的生态位偏好，我们提出杂种优势。我们的结果表明，杂交 P. fauriei 表现出更大的适应性，可以与母本 P. 小的竞争并占据最初的生态位。因此，我们认为母体 P.minor 经历了生态位转变，阐明了该杂交群体中生态位分化的模式。这些发现为蕨类植物中频繁发生的杂交提供了潜在的解释，并为蕨类植物杂交物种形成提供了新的见解，增强了我们对蕨类植物多样性的理解。