Abstract:

In order to investigate the genetic variations of different geographical populations of Pieris rapae Linnaeus in China, the ribosomal DNA gene interval transcribed spacer 1 (ITS-1) sequences of 79 indididuals from 16 areas were determined and analyzed. Upon these gene sequence data and using Pieris canidia as the outgroup, we reconstructed phylogenetic trees by means of neighbor-joining and minimum evolution analyses, aiming to clarify their biogeographical divergence pattern. The results of the sequence variation analyses showed that the sizes of the ITS-1 of Pieris rapae range from 337 to 458 nucleotides in length. Aligned with the ClustalW software, the total 347 sites, which contain 281 conserved, 63 variable and 16 parsimonious informative, were obtained. Meanwhile, for the whole population of this study, the nucleotide diversity Pi and the Theta (per site) Eta were calculated to be 0. 014 and 0.041, respectively. Moreover, total 48 haplotypes were identified and the haplotype diversity 0.989 was obtained by the software DnaSP. Additionally, the fixation index (F_ST) 0.351 (P<0.05) was calculated by the analysis of molecular variance (AMOVA) software. The result of phylogenetic analysis indicated no pronounced correlation between their haplotypes and the geographical regions. Based on the phylogenetic trees, it is inferred that the Pieris rapae in China probably colonized first in the Liaoning, Inner Mongolia and Beijing, and then spread to other areas by transportation of their host plants and migration of their adults.

Key words: Pieris rapae, geographical population, genetic diversity, phylogeography, ITS-1 sequences