遗传和环境对橘和枳物种形成的影响

The Role of Genetics and Environment in the Speciation of Citrus and Poncirus

生物分类的意义在于阐明不同物种之间的进化关系,遗传因素是物种形成的内因,环境因素是物种分化的外因。植物学二界分类系统表明橘和枳分属于柑橘属和枳属,这是植物分类学界普遍接受的观点。然而,“橘生淮南则为橘,生于淮北则为枳”的古语容易让老百姓误认为二者是同一物种。本研究通过文献综述梳理了橘和枳的起源和演化脉络,分析了环境因素对橘与枳在淮河流域乃至全国地理分布特点的影响;通过实地考察和形态学比较,描述了橘与枳五个明显的形态学差异;利用ITS序列分析了橘与枳的亲缘关系。本研究表明:橘和枳起源于同一个物种,两者的差异是在物种分化后,由于对环境的适应性不同而形成的;二者均属于真正柑橘组植物,但分属于其中的柑橘属和枳属,是不同的物种。该结果为学界和老百姓对橘和枳的进一步认识提供参考,也为理解遗传和环境因素共同影响物种分化提供帮助。

Biosystematics aims at throwing light on the relationships between different species in evolution, which is based on genetic and environmental factors. Botanical binary classification system indi-cates that Citrus and Poncirus belong to Citrus and Poncirus respectively, which is widely accepted among phytotaxonomic researchers. However, the old saying that Citrus is called “Citrus” in the south and becomes Poncirus when grown in the north conveys the stereotype that Citrus and Pon-cirus are the same species. Here, we clarified the origin and evolution of Citrus and Poncirus, and elaborated the influence of environment on their distribution within the Huaihe River Basin and China. We also described five morphological differences between them and analyzed their rela-tionship based on ITS sequences. We concluded that Citrus and Poncirus originated from the same species and differentiated due to adaptability. Both of them belong to True Citrus, but are in dif-ferent genera. The results can help to understand the relationship between Citrus and Poncirus and the roles of genetics and environment in speciation.