Multiple paternity in the leafcutter ant Atta colombica -: a microsatellite DNA study

An evolutionary understanding of the causes, correlates and consequences of multiple paternity in eusocial Hymenoptera (all ants, some bees and some wasps) relies on accurate estimation of this parameter at the species, population and colony level. We developed dinucleotide microsatellite DNA markers in order to study in detail the degree of multiple paternity in a population of the monogynous Panamanian leafcutter ant Atra colombica. These microsatellite markers were highly polymorphic such that nondetection caused by finite allelic diversity was very low (0.016). Hence, accurate information on the patterns of multiple paternity could be obtained. Genetic analysis revealed that in 33 out of 36 colonies two or more males had contributed genetically to the offspring. The mean number of fathers per colony was 2.6 and the mean effective paternity was 2.31. These are the highest values of effective paternity yet reported fur any ant species. We examined the patterns of paternity frequency in young and old colonies to test if within-colony genetic diversity is related to colony survival, but found no support for any relationship. Our results confirm previous nongenetic studies showing high levels of multiple mating by queens of higher leafcutter ants. We discuss our findings in relation to known patterns of polyandry and paternity in other eusocial Hymenoptera.