Genetic analysis of colony structure in polydomous and polygynous ant populations

Abstract

*[Most interactions between individuals of social insects occur in colonies. The correct identification of colonies is therefore crucial for most empirical studies which aim to test evolutionary theories based on properties at the colony level. In many ant populations, the identification of colonies is hampered by polydomy, i.e. that single colonies occupy several, spatially separated nests. Only few attempts have been made so far to develop genetical methods for analysing the structure of specific colonies. Three methods to solve this problem are presented: rare genotype sisterhoods (i.e. tracking rare genotypes or alleles), G-distance (i.e. a measure of genotypic heterogeneity derived from G-statistics), and neighbor relatedness (i.e. estimates of genetic relatedness for specific nest pairs). Our methods quantify the likelihood of nest pairs being con-colonial or non-colonial, and given sufficient genetical resolution, statistical tests can be applied. The methods proposed here are applied to a highly polygynous population of the red ant, Myrmica sulcinodis. In this population single colonies are found to inhabit 1-4 nests, and both monodomous and polydomous colonies coexist in dense clusters of nests.]