Analysis of genetic differentiation and phylogenetic relationship between Whitmania pigra and Hirudo nipponia based on ITS sequence

Abstract

To evaluate the genetic differentiation and phylogenetic relationship between Whitmania pigra Whitman and Hirudo nipponia Whitman. By the sequences of the rDNA internal transcribed spacer (ITS) the molecular phylogenetic tree was constructed by MP method using software MEGA 4.0. The average length of ITS was 857.2-861.2 bp. The A, T, G and C contents in this fragment were 25.12%, 28.28%, 17.34%, 29.29%, respectively. The GC content was higher than the AT content. Little sequence variation was observed in ITS gene fragments with in species, and transition in only 45 loci was revealed in 14 populations. 14 W. pigra and H. nipponia populations were clustered into 2 groups by MP phylogenetic tree. The results also showed that the intraspecific variation was dominated in variation types of W. pigra and H. nipponia. The classification result of W. pigra and H. nipponia and its adulterants based on DNA sequences are not totally consistent with those based on classification. It showed that a little of mutation of base in ITS sequences had occurred in the process of evolution, such as transition cites, transvertion cites among base or base gap.