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There is high within-nest relatedness for functional queens (with corpora lutea), nonfunctional queens (without corpora lutea), and workers in polygynous nests of Leptothorax acervorum. The high functional queen relatedness suggests that young mated queens are adopted back to their mother nest. Functional queen relatedness does not change with the number of queens present in the nest, suggesting that the number of generations of queens, on average two to three, is rather stable. Worker relatedness decreases with increasing number of functional queens per nest (Tables 5, 6). The number of queens contributing offspring to the nest (mothers), estimated from worker and functional queen relatedness, is lower than the number of functional queens, particularly in highly polygynous nests. Estimates of number of mothers in monogynous nests indicate that these nests previously were polygynous (Table 7). There is no correlation between nest relatedness and distance between nests, and budding-off, if present, thus appears to be a rare mode of nest founding (Table 8). There are no indications of inbreeding in the two populations studied since the frequency of heterozygotes is as high as expected from random mating (Table 4). Most likely, polygyny is the rule in L. acervorum and serves to secure the presence of queens in the nest.

One hundred and fifty one colonies of the ant L. acervorum comprising 815 queens were sampled in dry pine forest at nine sites in SE Sweden. 63°70 of the colonies contained more than one queen and of these 79% had more than one egg-laying (functional) queen, i.e. were polygynous. By using the electrophoretic variation at the PG1 locus a high overall relatedness (0.4) among queens from the same colony was found indicating that young queens are adopted by their mother nest. No spatial microdifferentiation in allele frequencies could be detected and it thus seems that despite restricted movements of queens there is a free gene flow in the populations.

The degree of activity of H. virgaureae in the field is largely dependent on air temperature, solar radiation, and wind velocity. Solar radiation increases body temperature above ambient. The butterfly orientates its back towards the sun and exposes the dorsal surface of the wings. At high temperatures they close the wings thereby minimizing the surface exposed to the sun. The optimal body temperature lies around 35°C as was indicated by laboratory experiments. In cloudy and cool to fairly warm conditions the butterfly is inactive. In sunshine the butterfly basks at low radiation intensities or low air temperatures while feeding (in males also flying) predominates at full sunshine or very high air temperatures (around 30°C). Males fly 5-10 times as much as females. A change from unfavourable to favourable weather is followed by an immediate increase in activity of the butterfly, which enables the butterfly to utilize short periods of sunshine.

Morphological and allozymatic analyses show that there are four .species -L. tuberum (mainly in the north) and L. nigriceps, L. "tubero-interruptus", and L. unijasciatus (sympatrically in the south) -in the Leptothorax tuberum group in West Europe north of the Alps, and that these species hybridize. The two commonly co-occurring species, L. nigriceps and L. unifasciatus, rarely hybridize, suggesting that premating isolating mechanisms have evolved, whereas the rare species, L. "cubero-interruptus", easily interbreeds possibly with all the other species of this group. There are distinct morphological gaps between the species, but hybridization tends to fill these gaps or even produces morphological copies (L. nigriceps x L. "tubero-interruptus") of a third species (L. tuberum).