. "8 Insect Societies as Divided Organisms: The Complexities of Purpose and Cross-Purpose--JOAN E. STRASSMANN and DAVID C. QUELLER." In the Light of Evolution: Volume 1. Adaptation and Complex Design. Washington, DC: The National Academies Press, 2007.
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In the Light of Evolution, Volume I: Adaptation and Complex Design
mature Atta colony is a huge and intricate operation. Millions of ants cultivate fungi deep underground. The nest has chambers a person could stand in, gardens tended by a suite of worker castes, including leaf processors who use microbial fungicides and have specialized organs to carry these symbionts (Currie et al., 2006). However, this metropolis of ants has but a single queen, and when she dies the colony dies: the fungus gardens are overrun by rogue fungi, the workers cease to rear brood, and the galleries ultimately collapse. This disaster could be avoided by the relatively simple matter of keeping on hand one or more backup queens. But this would risk unleashing competition among the queens that might harm the interests of both the current queen and her workers.
WORKER REPRODUCTION AND POLICING
The existence of dwarf queens shows that even larvae that are fed less than the normal queen amount can reproduce. This ability can also extend to workers. Workers are females that are morphologically or behaviorally specialized to forage, care for brood, and defend the colony. None of these tasks is enhanced by egg-laying, and yet workers in nearly all species maintain some ability to lay eggs. Workers in many species regularly do so, producing males because they are uninseminated. They have considerable incentive to do this because a worker is more related to her own sons (1/2) than to brothers (1/4) produced by her mother (Trivers and Hare, 1976).
In some species, the queen “polices” these worker-laid male eggs, eating them when she finds them. Indeed the elaborate provisioning and oviposition process of stingless bees described earlier may sometimes be less a matter of cooperative communication about the filling of the cell than a contest over who gets to fill it. All that actually needs to be accomplished is regurgitation of food into the cell by workers, laying of an egg by the queen, and then sealing of the cell by workers. As it is, many more workers than necessary surround the empty cell. When the queen approaches the empty cell she can be very aggressive toward the workers, who ritually either approach her or back away. The queen often aggressively solicits food from the workers, who nearly always refuse to provide it. After the cell is filled, the queen lays an egg in it. Interestingly, the workers close the cell with their abdomen in it, a position in which they might lay an egg, something that might account for the commonness of worker male production in stingless bees (Tóth et al., 2002b). [In some species, workers return later to sealed cells to open them and oviposit (Beig, 1972; Tóth et al., 2002a), which can succeed because the worker-laid male egg hatches quickly, and the larva hunts down and kills the older female larva in the cell.] The fact that these behavior patterns differ considerably