Multiple mating and facultative polygyny in the Panamanian leafcutter ant Acromyrmex echinatior

Queen mating frequency of the facultatively polygynous ant Acromyrmex echin atior was investigated by analysing genetic variation at an (AG), repeat mi crosatellite locus in workers and sexuals of 20 colonies from a single Pana manian population. Thirteen colonies were found to be monogynous, 5 colonie s contained multiple queens, whereas the queen number of 2 colonies remaine d unresolved. Microsatellite genotypes indicated that 12 out of 13 queens w ere inseminated by multiple males (polyandry). The mean queen mating freque ncy was 2.53 and the mean genetically effective paternity frequency was 2.2 3. These values range among the highest found in ants, and the results are in keeping with the high mating frequencies reported for other species of l eafcutter ants. Consistent skew in the proportional representation of diffe rent patrilines within colonies was found, and this remained constant in tw o consecutive samples of offspring. Dissections showed that all examined qu eens from multiple-queen colonies were mated egg-layers. The mean relatedne ss value among nestmate workers in polygynous colonies was lower than that for monogynous colonies. No diploid males were detected in a sample of 70 g enotyped males. Worker production of males was detected in one queenless co lony. We discuss our findings in relation to known patterns of multiple mat ernity and paternity in other eusocial Hymenoptera.