The Genetic Structure And Mating System Of Brandt's Vole (Lasiopodomys Brandtii)

Brandt's vole (Lasiopodomys brandtii) is a typical social herbivore rodent habited in grassland in Xilingol and Hulunbeier, Inner Mongolia, China. Numerous literatures reported its population structure and mating system, but now we still do not know those very clearly. In previous studies, population structure and mating system of Brandt's vole were analyzed mainly using behavioral and ecological methods. In this study, we analyzed the basic characteristics of the genetic structure and its seasonal changes of natural Brandt's vole populations using 19 microsatellite markers. And we also performed paternity analysis according to the theory of Mendelian, which could help to understand the mating system of Brandt's vole. Our main results were as follows:1. The development of microsatellite markers. A microsatellite-enriched Library of Brandt's vole was constructed using streptavidin-coated magnetic beads. Of the 80 clones sequenced, 49 (61.25%) were found to contain microsatellites with five or more repeats, and 25 loci were potentially suitable for primer design. Ten of 25 loci were detected with allelic diversity.2. The analysis of genetic structure. We analyzed the genotypes of 458 Brandt's voles using 19 microsatellite markers. The results showed that 19 loci were high polymorphism in 458 samples, of which 17 loci were highly polymorphic (PIC>0.5) and the other 2 loci were moderate. Mean polymorphism information content (PIC) was 0.710, ranged from 0.370 to 0.890. The mean number of alleles, the effective number of alleles, the observed and the expected heterozygosity values were 10.842, 4.679, 0.744 and 0.686, respectively. The UPGMA dendrogram of different colonies displayed that the space distance was not correlated with the genetic distance when the space distance was close, and the genetic distance agreed with the space distance when the space distance was far. In addition, the most of individuals in the same natural colony were clustered together and shared a close relationship. Thus, all of our results indicated that the kin relationship should be the basis of natural group formed. In different seasons, the genetic structure of Brandt's vole showed that there were 34 and 23 private alleles in spring and autumn, respectively. 3 private alleles had a higher frequency (P> 0.03) in spring, and 2 in autumn. So, we could think the genetic population was different between spring and autumn.3. The analysis of genetic mating system. Eleven pregnant females and their 93 embryos were genotyped and paternity analysis was performed using known-mother model using Cervus3.0 software. The results showed that 63% (49/93) of the embryos could be assigned the biological fathers and mating competition should be happened among males. For example, QY1201 had the maximum offsprings with all four pregnant females in the"Pop12"group, which suggested that QY1201 should be dominant in this group and maybe have the priority of mating. A female (82%, 9/11) could mate with more than males, and a male (28%, 5/18) could also mate with more than females in breeding season. Thus, we suggested that the genetic mating system of Brandt's vole has promiscuity.