Restricted dispersal determines fine-scale spatial genetic structure of Mongolian gerbils

Abstract

Restricted gene flow may cause positive spatial genetic autocorrelation of animal populations at fine spatial scales. The Mongolian gerbil Meriones unguiculatus is a territorial, social rodent. Territoriality may create social fences to restrict dispersal or gene flow of Mongolian gerbils to a short distance. Restricted dispersal may differentiate fine-scale spatial genetic structure of populations with increasing distances (i.e., isolation by distance [IBD]). Competition for mates and inbreeding avoidance may result in equal dispersal propensity and subsequently similar spatial genetic autocorrelation between males and females of monogamous gerbils. We genotyped 327 gerbils, live captured from 26 burrow systems on a 9-ha plot in northcentral Inner Mongolia, China, using seven microsatellite loci. Spatial genetic autocorrelation was positive within 80 m and became negative from 80 m to 200 m, suggesting restricted gene flow. Inter-group genetic and geographic distances were related positively, supporting the IBD model. Live trapping data demonstrated equal dispersal propensities of male and female gerbils. Restricted dispersal and social organization may determine fine-scale spatial population genetic structure of social rodents.

Keywords: Meriones unguiculatus; dispersal; isolation by distance; microsatellite analysis; social rodents; spatial genetic autocorrelation.

Figure 1.

Spatial genetic autocorrelations of (A) all genotyped individuals, (B) females, and (C) males of Mongolian gerbils in Inner Mongolia, China. Abscissa is the starting point of a distance class. Ordinate is spatial autocorrelation coefficient (rc) of genotypes. Two dashed lines along the x axis are the permutated 95% CIs of autocorrelations under the null hypothesis of a random distribution of genotypes in space. Vertical lines are the bootstrapped 95% CIs of mean genetic autocorrelation. Panel (D) is the relationship between pairwise inter-group Wright’s F statistic and geographic distance of Mongolian gerbils in Inner Mongolia, China.

Figure A1.

The spatial distribution of 26 burrow systems of Mongolian gerbils on 9-ha study plot in Inner Mongolia, China. Symbols “S1”, “S2”, … , and “S26” are the identification numbers of burrow systems. Numbers in parentheses are the numbers of the genotyped gerbils captured at the burrow systems.