Phylogeographical Patterns Based On Mitochondrial Cytochrome B Gene Of Great Gerbil (Rhombomys Opimus)

Great gerbil (Rhombomys opimus) is a typical small mammal species in northwest arid desert and semi-desert regions. To study the phylogeography of great gerbil will help us to understand the origin and the evolution of biodiversity and the arid environment variation process of Nei Mongol-Xinjiang.We examined DNA sequence variation in the mitochondrial cytochrome b gene of 41 great gerbils (Rhombomys opimus) from Inner Mongolia, Xinjiang and Gansu provinces and one from Isfahan, Iran in GenBank to better understand the Phylo geographical patterns in arid regions of China. We found that among the 1140 bp of the mitochondrial cytochrome b gene, 50 nucleotide sites were variable (4.39% in the full sequence), including 48 transition and 2 transversion. A total of 23 haplotypes were identified. Among the four populations, haplotype diversity was high, however nucleotide diversity was low. Gnetic variation occurred both within populations and among populations. Fst analysis showed that the differentiation was significant (P＞0.05) between the populations of semi-desert in center of Inner Mongoli (CIM) and Alxan desert (ALX), and extremely significant among other populations. Phylogenetic tree analysis based on haplotypes demonstrated three lineages of great gerbil. One lineage includes the specimen from China and a second lineage from Iran. The genetic relationship between Iranian and Chinese great gerbil was farther than between the two lineages from China. The Chinese lineage was estimated to be split before 93 thousand years. Nested Clade Analysis showed allopatric fragmentation and continuous population expansion existing in the historic population of great gerbil. The population expansion analysis indicated that the great gerbil might have experienced a population expansion in 11.9 thousand years ago. These results indicated that the great gerbil population might have been affected by the climatic oscillations in the last ice age.