雀形目鸟类核型种系发生初探

通过雀形目42科315种鸟类核型比较,确立了雀形目鸟类原始核型,与Takagi(1974)提出的鸟类原始核型相比较在它们之间不具统一性,通过二者的比较发现:雀形目鸟类原始核型中第1对染色体与非雀形目鸟类原始核型中第2对染色体相对应:雀形目的第2对染色体与非雀形目的第3对染色体相对应.从系统关系上讲,雀形目鸟类原始核型来源于非雀形目鸟类原始核型中第1对大染色体着丝点分裂而形成,再经过各种重排机制形成现代雀形目各科鸟类核型. 染色体研究表明:雀形目鸟类不为单系起源类群.其特点可以从以下两点证明:一是鸣禽类和亚鸣禽类A组染色体有着明显的不同,二是二者的核型进化趋势也是不同的.依据核型、化石资料以及古地理、古气候的资料,笔者提出亚鸣禽类起源于南美大陆,在上新世或早更新世中美陆桥变得明显时才可能进入北美以及伸入欧亚大陆;鸣禽类是起源于旧大陆的类群,在气候和地理条件适宜的前提下进入新大陆,从而进一步适应辐射。

THE PHYLOGENETIC RELATIONSHIPS OF PASSERIFORMES KARYOTYPES

The paper concers about the phylogenetic relationships of passeriformes by means of cladistic analysis of the chromosome morphology. By the comparative analysis of karyotypes of 315 species of 42 families in passerine,it has been found that they share the common characteristics:the 1st pair of chromosome is 18. 89 TCL and m/sm type,which corresponds to the 2nd pair of primitive karyotypes in nonpasserine who is 19. 00 TCL and m/sm type. The 2nd pair of chromosome in passerine is 14. 02 TCL and st/t type, which corresponds to the 3rd pair of chromosome in nonpasserine who is 15. 00 TCL and st/t type. The 1st pair of primitive karyotypes in nonpasserine is 25. 25 TCL and m type,which has not been found in passerine. It seems plausable that the puimitive karyotype in passerine might been evolved from the primitive karyotypes in nonpasserine by centric fission of the first pair of chromosomes in nonpasserine. Two major evolutional lineage would be diveded according to the karyotype characteristics of passerine:the suboscines might originated from Southern Hemisphere and probably did not immigrate into Northern American Land until late pliocene or pleistocene, when a Central American land bridge became established. The oscine probably originated from the Old World, then might arrived in the New World by the medium of BeTing,hence gave rise to the New World nine-primaried oscines radiations.