[Objective]The aim was to prove that the mitochondrial genes of Cyt b and 12S rRNA with different evolutional rates have effects on the topological structures of phylogenetic trees.[Method]The complete sequences of Cyt b and 12S rRNA from 15 species in 12 families of snakes were downloaded and extracted from GenBank,while their molecular phylogenetic trees were constructed by Maximum Likelihood（ML） method with GTR ＋I ＋G substitute model based on PAUP4.0 software.[Result]With the same software,methods and species,the difference in topological structures of phylogenetic trees was mainly due to different evolutional rates of Cyt b and 12S rRNA genes.[Conclusion]In studies on phylogenetic trees,aimed to different research species and purposes,phylogenetic trees should be constructed by choosing the correct and appropriate genes.
[Objective] The aim was to carry out RAPD analysis on genetic diversity of Varanus salvator. [Method] 20 random primers were used for PCR amplification of genomic DNA of 36 individuals of V. salvator. [Result] 10 primers could produce highly reproducible RAPD bands. A total of 2 952 DNA fragments were successfully amplified. Each individual got 82 amplified bands on average,47 of which showed polymorphism. The polymorphic locus percent was 57.32%. The genetic distance among 36 individuals ranged from 0.035 9 to 0.335 9 with an average of 0.135 9. The Nei＇s gene diversity index （H） and Shannon＇s information index （I） were 0.181 9 and 0.263 0,respectively,indicating that V. salvator had greater genetic diversity. [Conclusion] The phylogenetic tree was inferred by using UPGMA analysis,it was found that the 36 individuals could be classified as one group,and there was no obvious population differentiation.
