Analysis of genetic variation among geographic populations of Calliptamus italicus in Xinjiang based on mitochondrial Cytb gene sequences

Author of the article:XU Ye1** MAI Ji-Wei2 LI Rui-Xue1 XU Li-Feng1 YU Bing-Jie1 YUAN Liang1 ROMAN Jashenko3 JI Ron

Author's Workplace：1. International Research Center of Cross-border Pest Management in Central Asia, Key Laboratory of Conservation and Management of Species Diversity in Xinjiang, College of Life Sciences, Xinjiang Normal University, Urumqi 830054, China; 2. School of Life Sciences, Lanzhou University, Lanzhou 730000, China; 3. Al-Farabi Kazakh National University, Almaty 050038, Kazakhstan

Key Words： Calliptamus italicus; mitochondrial Cytb gene; geographic populations; genetic differentiation; gene flow

Abstract： [Objectives]  To analyze the genetic variation among different geographic populations of Calliptamus italicus in desert and semi-desert steppe in Xinjiang, and to reveal the molecular and biological mechanisms underlying recent persistent and serious outbreaks of this pest. [Methods]  Specimens of C. italicus were collected from 10 different geographic populations to obtain a total of 100 full-length sequences of the mitochondrial cytochrome b (Cytb) gene (1 140 bp). We then used DnaSP 5.0 and Arlequin 3.5 software to clarify the genetic structure, differentiation, and molecular variances, within and among populations. A Maximum Likelihood phylogenetic tree and a diagram of the haplotype network of Cytb were constructed. [Results]  We detected 54 haplotypes among the 100 full-length sequences. The total haplotype diversity index (H_d) was 0.890 and haplotype diversity among the different geographical populations ranged from 0.818 to 1.000. The total fixed coefficient (F_st), total genetic differentiation coefficient (G_st), and total gene flow (N_m) were 0.0178, 0.0189 and 13.84, respectively. In addition, the genetic variation between populations (3.31%) was much less than that within each population. These results indicate that the C. italicus populations investigated in this study are stable in size and have not undergone recent population expansion. Geographic distance may not, therefore, be an important factor affecting the genetic distance between different populations. [Conclusion]  Gene exchange occurs frequently between different geographical populations of C. italicus in Xinjiang, increasing the genetic variation within populations and thereby enhancing their ability to adapt to different environmental conditions. This situation may be related to recent persistent and serious outbreaks of C. italicus in Xinjiang.