Characterization of small populations with microsatellite markers on mousechromosome 11

Microsatellites of mouse chromosome 11 were used to characterize genomic ch anges on this chromosome in small populations. Populations were kept under different mating principles to (1) minimize the rate of inbreeding (MRI) an d (2) to conserve the phenotypes of the basic population (BPC). Both popula tions were generated from a common base population with an effective popula tion size of 20 mating pairs. After 13 generations the phenotypic values of body weight did not differ significantly from the initial population in bo th mating variants. However, the estimated coefficient of inbreeding was si gnificantly increased in variant BPC compared to MRI. Microsatellite marker analysis proved the occurence of significant differences in allele frequen cy distributions between both mating variants as recorded at the 13th gener ation. Significantly, a complete loss of specific microsatellite alleles wa s evident in both mating variants. The number of lost alleles in the varian t BPC was twice as high as in the variant MRI. Thus, microsatellite analyse s confirmed the expectation that the consequent reduction of inbreeding con tributes to both reduction of genetic losses and maintenance of the origina l phenotypes.