团花锦蛇、绿锦蛇和三索锦蛇的核型及Ag-NORs

KARYOTYPES AND Ag-NORs OF ELAPHE PRASINA , E. DAVADI AND E. RADIATA ELAPHE (REPTILIA: COLUBRIDAE)

报道了锦蛇属团花锦蛇 (E .davidi)、绿锦蛇 (E .prasina)和三索锦蛇 (E .radiata) 3个种的核型和Ag-NORs ,团花锦蛇的核型 2n =36 (8V + 6sV + 2I + 2 0M) ;绿锦蛇的核型 2n =36 (7V + 7sV + 2I + 2 0m) ,三索锦蛇的核型 2n =40 (6V + 3sV + 2sI + 5I+ 2 4m) ;①团花锦蛇和绿锦蛇的染色体数目和结构与此属大多数种的相似 ,;②此属种类的性染色体为ZW型 ,绿锦蛇的性染色体为第 4对大染色体 ,三索锦蛇的为第 5对大染色体 ,团花锦蛇由于为雄性 ,未见染色体异型 .③Ag -NORs在数目及在染色体上的位置均不相同 ,团花锦蛇的NORs在第 9对染色体上 ,数目为 2个 ;绿锦蛇的NORs在第 5对染色体上 ,数目为 4个 ;三索锦蛇的NORs在第 4对大染色体上 ,数目为 4个 ;④我们发现三索锦蛇较为特殊 ,其染色体数目、形态、性染色体的位置和形态及Ag -NORs均与其它种类不同 .可能的原因是此物种在核型演化过程中发生过染色体断裂和重排事件 ,提示三索锦蛇可能是一个特化的类群 .⑤锦蛇属的种类可分为包括三索锦蛇为特殊的一组的 4个组 .图版 1表 2参

Karyotypes and Ag NORs of 3 species; Elaphe prasina, E. davadi and E. radiata femalewere reported. The karyotypes of E. prasina and E. davadi were 2 n =8V+6sV+2I+20m (male) and 2 n =7V+7sV+2sI+20m (female), respectively. The Karyotype of E. radiata was 2 n =6V+3sV+2sI+5I+24m. Considering other species in Elaphe, the results suggested that: ① the numbers and morphological structures of E. prasina andE. davadi were homomorphic as those of most species in this genus; ② Sex chromosomes of the 3 species were heteromorphic which resulted from Z and W differences in chromosome sizes and centromere positions; ③ The numbers and positions of NORs in the 3 species were different. ④ E. radiata was distinct at chromosomal level. The differences in its karyotype, sex chromosomes and the NORs may suggest abrupt chromosomal event in the evolution of E. radiata. ⑤ The species in Elaphe could be divided into 4 groups including E.radiata as a specific group. Fig 1, Tab 2, Ref 18