基于生物学物种定义探讨物种形成理论与验证的研究进展

Advances in speciation theories and their verifications based on the biological species concept

物种形成是进化生物学研究的一个永恒主题,由于生物群体进化是连续和动态的,物种界限变得难于界定。本文首先讨论了3种地理物种形成模式(同域、邻域及异域),并分析了近期报道的研究证据。其次,评述了合子后生殖隔离机制的分子遗传基础和应用群体基因组数据分析的证据,包括BDMI模型(Bateson-Dobzhansky-Muller incompatibility)、QTLs(quantitative trait loci)、霍尔丹法则及大X染色体效应。最后,探讨了交配系统作为合子前隔离机制之一与物种形成的关系,认为近交或自交通过扩大种群遗传结构分化,增强不同交配系统的种群间不对称基因渐渗,或种群间无基因渐渗等途径,促进新物种形成。已知植物交配系统的演化更倾向于从异交(或自交不亲和)向自交(或近交亲和)方式,花性状和基因组的分化推动形成所谓的自交综合征,研究交配系统驱动或强化物种形成模式对认识植物物种形成机制有重要意义。

Background&Aim:Speciation is a constant theme in the study of evolutionary biology.The nature of the dynamics and continuity of population evolution makes it hard to define the concept of species.Understanding the mechanisms of speciation remains crucial in the fields of evolutionary biology,taxonomy,conservation biology and biodiversity.Here we revisited the existent theories of speciation and reviewed the recent advances in empirical study.Progresses:We discussed three geographical patterns of speciation(sympatric,parapatric,and allopatric speciation)and reviewed the corresponding empirical evidence from recent studies,based on the classical concept of biological species coined in terms of reproduction isolation.We further discussed the molecular genetics basis of postzygotic reproductive isolation and the evidence derived from analyses of applying population genomic data,including BDMI(Bateson-Dobzhansky-Muller incompatibility),QTLs(quantitative trait loci)analysis,Haldane’s rule and the large X-chromosome effects.We finally discussed the relationship between mating system,one of the pre-zygotic isolation barriers,and speciation.We inferred that selfing or inbreeding could drive speciation via either increasing population genetic differentiation or impeding gene flow between populations of different mating systems,or both.Prospects:More evidence is needed to verify speciation theories.In addition,given the more frequent transitions to selfing from outcrossing in plant species,both flower characters and genomic differentiation could drive the so-called selfing syndromes.It is significant to clarify the role of mating system as a driver or as a reinforcer in plant speciation.