A reassessment of the mating system characteristics of the army ant Eciton burchellii

Abstract

In a recent study, Denny et al. (2004a) showed that queens of the army ant, Eciton burchellii, mate with multiple males and presented estimates suggesting that they mate with more males than queens of any other ant species so far investigated. They also inferred that data were consistent with queens being inseminated repeatedly throughout their life, which would be exceptional among the social Hymenoptera and contradictory to predictions from kin selection theory. In the present study, we reanalyze these data using new software and supplement them with similar microsatellite data from other colonies of the same species. Mating frequencies in E. burchellii are indeed very high (mean observed and effective queen-mating frequencies of 12.9 each) but considerably lower than the previous estimates. We show that the number of patrilines represented in the first worker offspring of a young queen is lower than in older queens but suggest that this may be due to initial sperm clumping in the queen's sperm storage organ, rather than to repeated inseminations. Moreover, we found no evidence for repeated mating by genotyping sequential worker generations produced by a single old queen, showing that she did not obtain new inseminations despite ample opportunities for mating.

Multiple mating in the ant Cataglyphis cursor: testing the sperm limitation and the diploid male load hypotheses

“…Obligate multiple mating by queens has evolved repeatedly in bees, wasps and ants Brown and Schmid-Hempel, 2003;Boomsma et al, 2005). For instance in ants, where effective queen mating frequency (M e,p ) is usually lower than 2 (Boomsma and Ratnieks, 1996;Strassmann, 2001;), high polyandry levels have been reported in the genera Atta (M e,p = 3.1, Murakami et al, 2000), Cardiocondyla (M e,p = 3.3, Lenoir et al 2007), Acromyrmex (M e,p = 3.9, Boomsma et al 1999), Pogonomyrmex (M e,p = 6.8, Cole and Wiernasz, 2000), Neivamyrmex (M e,p = 12.8, , Eciton (M e,p = 12.9, Kronauer et al, 2006), Dorylus (M e,p = 17.5, Kronauer et al, 2004), and Aenictus (M e,p = 18.8, .…”

Gene flow is maintained by polyandry and male dispersal in the army antEciton burchellii

“…Following Kronauer et al (2006b), we first deduced the genotypes of the queens and their mates by running MateSoft version 1.0 (Moilanen et al 2004) with all known alleles at equal frequencies. In some cases, MateSoft returns two or more alternative genotypes accompanied by their respective weighted probability, which is calculated based on the allele frequencies initially given.…”

“…Here, we address these aspects in a Mexican population of the army ant E. burchellii. By genotyping enough worker offspring of the highly polyandrous Eciton queens (Kronauer et al 2006b), which can be easily collected in the field, it is possible to deduce the genotypes of all the siring males of a particular colony. Based on these inferred male genotypes, we reconstructed the genotypes of their maternal queens, quantifying the number of colonies from which these males came.…”

Genetic diversity, worker size polymorphism and division of labour in the polyandrous ant Cataglyphis cursor

“…Social Hymenoptera (ants, bees, wasps) are no exception to this rule and queens of several species mate multiply. Multiple mating is prominent in eight genera, the honeybee (Apis: Palmer & Oldroyd 2000), the yellow jacket wasps (Vespula: Goodisman et al 2002), the seed harvester ants (Pogonomyrmex: Rheindt et al 2004), the higher leaf-cutting ants (Atta and Acromyrmex: Boomsma et al 1999;Sumner et al 2004), the army ants (Dorylus and Eciton: Kronauer et al 2004;Kronauer et al 2006) and the desert ant (Cataglyphis: Pearcy et al 2004a). This suggests that polyandry has benefits to queen fitness.…”