Sequences of mitochondrial D-loop and Cyt b gene of 24 individuals of

Squaliobarbus curriculus

which were sampled from four populations in Yangtze River and Pearl River were determined. Using PCR amplification and sequencing

598bp of D-loop partial sequences and 752 bp of Cyt b partial sequences were obtained. In D-loop sequences

a total of 67 polymorphic sites defined 18 distinct haplotypes. And 34 parsim-info

40 transition

15 transversion and 14 insert/lacuna loci were found. The average content of A

T

C and G was 33.7%

35.1%

17.5% and 13.7%

respectively. In Cyt b sequences

72 polymorphic sites and 18 haplotypes were defined

and 68 parsim-info

60 transition

15 transversion and no insert/lacuna loci were found. The average content of A

T

C and G was 29.3%

26.4%

29.8% and 14.5%

respectively. The mean haplotype diversity (H)

the average number of nucleotide difference (K) and nucleotide diversity (π) for D-loop sequences were 0.9638

16.543 5 and 0.0284

respectively. Accordingly

the values for Cyt b were 0.971 0

31.855 1 and 0.042 6

respectively. The results suggested that both D-loop and Cyt b genes showed high genetic diversity in

S. curriculus

among which the majority existed within populations. Based on population pairwise genetic distances and F

ST

there were obvious genetic differences between Yangtze River and Pearl River for

S.curriculus

Molecular phylogenetic tree and analysis of molecular variance (AMOVA) also supported this result. The interpopulation genetic distances of Cyt b in the same water system were less than D-loop; while those in the different water system were more than D-loop. So for Cyt b

the more interpopulation genetic diversity was

the smaller genetic distances and F

ST

were; the less interpopulation genetic diversity was

the larger genetic distances and F

ST

were

which might be closely related to difference of evolutionary rate between D-loop and Cyt bgene.