Chromosome Diversity of Tibetan Fishes

This article reports chromosome diversity of 12 species of Tibetan fishes.The results of our experiment are as follows:1)Chromosome number and karyotype formula of Glyptosternum maculatum are 2n=48=20 m+12 sm+10 st+6 t,with other two kinds of 2n=44 and 2n=42,which doubt the Rens conclusion that it was the most advanced species in Sisorid fishes.2)Chromosome number and karyotype formulae of Triplophysa tibetana,Oxygymnocypris stewartii,Schizopygopsis younghusbandii,Schizothorax (Racoma) o connor and Schizothorax (Racoma) waltoni are 2n=50=14 m+4 sm+22 st+10 t,2n=86=24 m+12 sm+22 st+18 t,2n=94=22 m+8 sm+46 st+18 t,2n=106=24 m+26 sm+30 st+26 t,2n=112=26 m+24 sm+28 st+34 t,respectively,which differ from former conclusions.3)In this article,chromosome number,karyotype formulas and orignal pictures of Triplophysa microps and Gymnocypris waddelli,and karyotype formula,original picture of Schizothorax (R.) macropogon are firstly reported as 2n=50=16 m+12 sm+12 st+10 t,2n=94=24 m+14 sm+22 st+34 t,2n=102=20 m+28 sm+22 st+16 t,respectively.4)Chromosome number of Gymnocypris dobula is 2n=66,the least in Schizotho racin fishes,while that of Ptychobarbus dipogon is 2n=424-432,mostly rare in Vertebrata,which need further research. Lastly,the authors consider chromosome diversity among each species and genus in three groups (Schizothoracines,Cobitids and Sisorids) of Xizang (Tibet) fishes is abundant,showing not only obvious difference among species,genus and groups,but variation in one species,even in individual.It is supposed that this is concerned with the unstable surrounding during speciation.For a certain confidence in chromosome variation,only stable karyotype can be used as proof in taxonomy and evolution.