首页 > 分享 > 一个种还是多个种? 简化基因组及其形态学证据揭示中国白桫椤植物的物种多样性分化

一个种还是多个种? 简化基因组及其形态学证据揭示中国白桫椤植物的物种多样性分化

花匠小妙招
2025-01-10 10:44

摘要：

物种是生物多样性的基本单元, 生殖隔离被认为是物种形成的关键; 然而物种并不是静止的而是处于不断的分化演变之中, 已经稳定成型但尚未到达分化后期的物种可能存在不完全的生殖隔离。对于物种的认识不能单从某一侧面或局部特征来界定, 而应通过“整合物种概念”来确定物种地位。Flora of China记载了中国产白桫椤属(Sphaeropteris) 2种, 即白桫椤(S. brunoniana)和笔筒树(S. lepifera), 并认为原产中国海南的海南白桫椤(S. hainanensis)和白桫椤为同一物种而将其并入白桫椤; 但海南白桫椤在形态上已出现了分化。为探讨白桫椤及其近缘物种的亲缘关系和物种多样性分化的情况, 本文采集到9个居群共21个样本, 通过GBS简化基因组测序技术获得单核苷酸变异位点(SNP), 进行系统发育树的构建和主成分及遗传结构的分析, 并结合叶片数量性状的统计分析和孢子形态的观察测量。结果表明, 海南白桫椤不仅与云南产白桫椤的基因型不同, 且在叶片特征和孢子纹饰上有明显差异; 但两个居群的生殖隔离较弱, 在广西沿海地区形成杂交产物, 其叶片特征为亲本的中间类型。因此, 我们认为海南白桫椤是由于地理隔离而形成的一个处在分化路上的物种, 建议恢复其物种地位; 广西产白桫椤为自然杂交群体, 应另处理为独立的自然杂交分类群——广西白桫椤(S. brunoniana × hainanensis)。

关键词: 白桫椤属, 海南白桫椤, 物种分化, 自然杂交, 基于测序的基因分型, 单核苷酸多态性

Abstract

Species are not static, but in the process of continuous differentiation and evolution. In this context, reproductive isolation is considered the key to most speciation events. However, species that may be only partially reproductively isolated may disturb our understanding of a species, as stated by ‘The integrative species concept’. In the Flora of China, Chinese Sphaeropteris contains two species, S. brunoniana and S. lepifera. S. brunoniana is thought to be the same species as a Hainan native, S. hainanensis, however, S. hainanensis seems to have differentiated morphologically. This study further explores the genetic relationship between S. brunoniana and its related species by collecting 21 samples from 9 populations for GBS reduced-representation genome sequencing for phylogenetic analysis. Using both genetic and morphological data, our results indicate that S. hainanensis differs genetically from S. brunoniana, but is also morphologically distinct based on leaf characteristics and spore ornamentation. Although the reproductive isolation of the two populations is weak, hybrids are formed in the coastal areas of Guangxi and leaves mimic intermediate morphology between parents. Therefore, our results suggest that S. hainanensis is in the process of speciation due to geographic isolation and suggests to restore its species status. S. brunoniana × hainanensis which the sample from Guangxi should be considered an independent natural hybrid taxon.

Key words: Sphaeropteris, S. hainanensis, speciation, natural hybridization, GBS, SNP