A Preliminary Study On The Genetic Diversity Of Tamarisk Gerbil (Meriones Tamariscinus) And Great Gerbil (Rhombomys Opimus) From Mongolia-Xinjiang Region

Tamarix gerbil(Meriones tamariscinus) and Great gerbil (Rhombomys opimus) are two relatively wide-distribution species in Mongolia-Xinjiang Region, and are important indicator species of biological diversity in arid landscape. We determined mitochondrial DNA (including Cyt b gene and D-loop control region) sequence of 1569bp from 45 tamarisk gerbil and got 7 microsatellite loci data for 121 great gerbils. Based on the DNA data, we studyed the genetic differentiation and genetic patterns of tamarisk gerbil and great gerbil relative to the landscape of Mongolia-Xinjiang.Combining the mitochondrial Cyt b gene (1140bp) and D-loop control region (429bp), a total of 1569bp were used as molecular markers. Based on mtDNA sequences analysis, we calculated the haplotype diversity, nucleotide diversity, and phylogenetic structure of the local populations, and then discussed the geographical differentiation of the species. A total of 142 variable sites accounting for 9.05% of the total sequence were determined from 45 samples, including 34 single-state sites,108 parsimony informative sites. No base insertion or deletion was detected. A total of 33 haplotypes were defined. Haplotype-based phylogenetic tree and haplotype network showed the 45 tamarisk gerbils clustered into two branches, of which Ili Basin branch was more primitive one. The divergence time between them was 0.24Ma years ago, about in Lushan glaciation. The population had a rapid recession in the past 1,5000 years, as may be a result from the Last Glacial Maximum. Based on the phylogeographic patterns inferred from the genetic variation in mtDNA Cyt b gene and D-loop region, we suggest that the population in Ili Basin should belong in M. t. jaxartensis, and those in Jungar Basin, Gansu and Inner Mongolia should be regarded as M. t. satchouensis.A total of 111 alleles from 7 microsatellite loci were detected, the average number of alleles per locus was 15.86. AF947 (PIC=0.27) sites and AF939 (PIC= 0.45) were moderate polymorphism, the other sites have high polymorphism. The average expected heterozygosity (He) and observed heterozygosity (Ho) are 0.58, 0.49, that shows great gerbil population has rich genetic diversity. This may be reasult from the Pleistocene ice age and geographic resistance caused great gerbil to be limited in fragmentation habitats. AMOVA analysis showed that the genetic variability of the great gerbil occurred within populations (97.57%). Through Bottleneck analysis showed that the great gerbil population in Alxan desert and North Xinjiang desert has a population bottleneck.