Extreme queen‐mating frequency and colony fission in African army ants

Abstract

Army ants have long been suspected to represent an independent origin of multiple queen-mating in the social Hymenoptera. Using microsatellite markers, we show that queens of the African army ant Dorylus (Anomma) molestus have the highest absolute (17.3) and effective (17.5) queen-mating frequencies reported so far for ants. This confirms that obligate multiple queen-mating in social insects is associated with large colony size and advanced social organization, but also raises several novel questions. First, these high estimates place army ants in the range of mating frequencies of honeybees, which have so far been regarded as odd exceptions within the social Hymenoptera. Army ants and honeybees are fundamentally different in morphology and life history, but are the only social insects known that combine obligate multiple mating with reproduction by colony fission and extremely male-biased sex ratios. This implies that the very high numbers of matings in both groups may be due partly to the relatively low costs of additional matings. Second, we were able to trace recent events of colony fission in four of the investigated colonies, where the genotypes of the two queens were only compatible with a mother-daughter relationship. A direct comparison of male production between colonies with offspring from one and two queens, respectively, suggested strongly that new queens do not produce a sexual brood until all workers of the old queen have died, which is consistent with kin selection theory.

Genetic diversity within honeybee colonies increases signal production by waggle-dancing foragers

“…Synergism between dance communication and multiple mating in honeybees may be one of the main selective forces propelling the evolution of the extreme polyandry that characterizes this monophyletic group. Where extreme polyandry is found in other highly derived eusocial insect taxa, such as harvester and army ants (Denny et al 2004;Kronauer et al 2004;Rheindt et al 2004;Wiernasz et al 2004), intracolonial genetic diversity may play a similar role in their complex and well-organized foraging efforts.…”

No intracolonial nepotism during colony fissioning in honey bees

“…Although queens in most social insect species do not mate with multiple males (Strassmann 2001), polyandry is prominent in certain taxa including yellow jacket wasps (Vespula, Ross 1986), leaf-cutter ants (Atta, Fjerdingstad et al 1998;Acromyrmex, Boomsma et al 1999), army ants (Eciton, Denny et al 2004; Dorylus, Kronauer et al 2004), harvester ants (Pogonomyrmex, Rheindt et al 2004;Wiernasz et al 2004;Pol et al 2008), desert ants (Cataglyphis, Timmermans et al 2008) and honey bees (Apis, Estoup et al 1994;Tarpy & Nielsen 2002). One consequence of this polyandry is that the females in a colony (queens and workers) are not all full-sisters.…”

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, .…”