Hi all
Maybe the question should be not why diutinus bees lives so long, but why summer bees' lives are so short. It makes sense to invest less in the bees which are assigned the highest risk tasks (guarding, foraging, etc.) and are likely to die anyway from external causes, while preserving a core of long lived bees to ride out hard times (winter, migration, etc.)
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The “disposable soma” theory is capable of explaining the bimodal longevity distribution of honeybees when interpreted in a group selection context.
The “disposable soma” theory is based on optimal allocation of metabolic resources between somatic maintenance and reproduction. the disposable soma theory predicts the establishment of a facultative age determination mechanism. It also predicts that the winter bee will have a functioning set of mechanisms ensuring somaticmaintenanc e by preventing intrinsicdeterioration of the organism for several months, while the forager will not.
The bimodal longevity distribution of honeybees can be considered to be an emergent group trait phenomenon at the colony level. The honeybee worker does not normally reproduce, and at the group level it can be considered to be soma. In this group selection context, it makes sense to talk about optimal allocation of metabolicresourc es between somaticmaintenance and reproduction. Thus, by changing focus from the level of the individual to the level of the colony, the disposable soma theory can be meaningfully applied. In the summer time, the bees need to forage, and as foraging is risky, they are not likely to live long (Visscher & Dukas, 1997).
In this case, there will be a group trait selection against investing resources that may increase the potential lifespan of the workers. In the wintertime, however, when there is no risky foraging and the colony has to stay alive for several months before it can continue making reproductives, there will be group trait selection for allocating enough resources to keep the workers alive for a long time.
Amdam, Gro Vang, and Stig W. Omholt. "The regulatory anatomy of honeybee lifespan." Journal of Theoretical Biology 216.2 (2002): 209-228.
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