GENETIC-STRUCTURE OF NESTS IN THE ANT FORMICA-SANGUINEA

1. Polymorphism at an enzyme locus encoding for malate dehydrogenase was studied in 92 nests of the ant Formica sanguinea, mainly in Finland. Four alleles segregated at the locus. In seven nests all workers were homozygous for a single allele. In all other nests heterozygotes were observed. Of the nests, 75% were two-genotype nests having mainly one homozygous and one heterozygous worker genotype. 2. Each single nest could be explained as the offspring of one gyne, but this interpretation does not agree with the expectations at the population level. The distribution of different nest types was compared with the results obtained by various computer-simulated reproductive strategies. The observations were best explained by several related, single-mated gynes per nest, and by one gyne possibly dominating the egg-laying. This agrees with earlier field observations and is also supported by the level of genetic relatedness among nestmates. 3. In two successive years, the average coefficients of relatedness (b±SE) among workers of a single nest in one population were 0.420±0.098 and 0.311±0.124. As the coefficient of relatedness of the female brood to the workers of the same nest was 0.378±0.173, the brood that the workers care for is less closely related to them than their own offspring would be. The relatedness of the male brood to the workers was b=0.616±0.402. Worker ants of neighbouring nests were related to one another, b=0.248±0.093, presumably due to existence of sister nests. © 1979 Springer-Verlag.