We developed microsatellite loci from the genome of the temperate fore
st ant Myrmica punctiventris and used them to study colony genetic str
ucture. We report here primer sequences for three new microsatellite l
oci, and also show that previously published primers isolated from a c
ongener amplify loci in our study species. Successful cross-priming of
loci in four other ant species further illustrates that investigators
may now be able to sidestep the labour of developing new microsatelli
te systems. The microsatellite data allowed us to estimate coefficient
s of relatedness far more precisely than was possible from previous al
lozyme work. Furthermore, we obtained evidence of complex colony struc
ture in this population: while overall colonies showed a relatedness s
tructure that is consistent with values expected for a single, once-ma
ted queen (Hamilton 1964), some nests contained worker-laid males, whi
le others included members of at least two families. We used these dat
a to examine reproduction as a function of genetic structure, and foun
d evidence of sex ratio compensation in this species: nests containing
worker-laid males allocated more energy to reproduction and had stron
gly male-biased allocation ratios relative to others in the population
.