Long-term stability of allozyme frequencies in a wood lemming, Myopus schisticolor, population with a biased sex ratio and density fluctuations.
Wood lemming (Myopus schisticolor) populations are characterized by female biased sex ratios and cyclic variations in population size. Both of these characteristics are assumed to reduce genetic variation and thus affect the evolutionary adaptation of the species. We addressed these questions by studying the genetic structure of a wood lemming population from eastern Finland by isozyme markers during a 21-year period, which corresponds to 40-50 generations. Contingency tests showed that genotypic proportions conformed to Hardy-Weinberg equilibrium in each of the four sampling years. Among the temporal replicates, allele frequencies differed most by 0.14 and were not significant. Genetic variation was also stable and fairly high with a mean observed heterozygosity of H = 0.057. Variability in the Heinavesi population was higher than previously reported in wood lemming. The difference was mainly caused by variation at a phosphoglucomutase locus that was monomorphic in earlier studies. Significant linkage disequilibrium was observed in three of the comparisons but the disequilibrium did not appear consistently in all years. This pattern was also evidenced by the variance components, which indicated that selection favoured for specific allele pairs only in few subsamples.
Vuorinen
J A
JA
Department of Biology, University of Joensuu, PO Box 111, FIN-80101 Joensuu, Finland. jukka.vuorinen@joensuu.fi
Eskelinen
O
O
D000818:Animals; D003411:Arvicolinae / Q000235:genetics*; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D014644:Genetic Variation; D005828:Genetics, Population; D015810:Linkage Disequilibrium / Q000235:genetics*; D010733:Phosphoglucomutase / Q000235:genetics*; D040641:Quantitative Trait Loci / Q000235:genetics*; D012744:Sex Ratio
D010733:Phosphoglucomutase