Genetic Relationships of The Specialized Schizothoracine Fishes Inferred From Random Amplified Polymorphic DNA Analysis

The specialized schizothoracine fishes belong to subfamily Schizothoracinae (Cyprinidae).Compared to other fishes in the same subfamily,the specialized schizothoracine fishes have the following characters:1)only 1 pair of barbels,2)2 rows of pharyngeal teeth,3)scales degenerated,and even degenerated entirely in genus Gymnodiptychus (Cao et al.,1981).There are 9 species and subspecies belonging to 3 genera ［Diptychus (Steindachner,1866),Ptychobarbus (Steindachner,1866) and Gymnodiptychus (Herzenstein,1892)］ in this group.In this paper,random amplified polymorphic DNAs (RAPDs) were used to investigate genetic relationships among 22 individuals of the fishes,which represent 6 species and 4 genera,Schizothorax,Diptychus,Ptychobarbus and Gymnodiptychus respectively.234 RAPD markers were observed by using 37 arbitrary primers (10 bp).The molecular phylogenetic tree constructed by NJ (Neighbor-joining) method indicated that these 22 individuals could be divided into 6 clusters (each cluster represents one species).Upon the relationships among the 3 genera,Diptychus,Ptychobarbus and Gymnodiptychus,the conclusion was the same as that concluded from the phylogenetic analysis by using morphological characters.The result showed that RAPD could be used to study the phylogenetic relationships of closely related genera.