Hi all
I was recently told by a friend that he thought that honey bees were once monandrous, and that multiple mating evolved over time. This was according someone at the University, who would be expected to know. No, I said, honey bees are all polyandrous. The ancestors of honey bees would likely have been monandrous but the transition is beyond our reach, because there is no way to determine any of this info from fossils. Hughes & al state

> Our analysis shows that monandry was the ancestral state for all eight of the independent origins of eusociality. All females are monandrous in the only eusocial sphecid wasp. Females in the three eusocial lineages of halictid bees mate either singly or very rarely doubly. 

> Among the corbiculate bees, all stingless bees are monandrous, all honeybees are polyandrous, and bumblebees are ancestrally monandrous with facultative low polyandry being derived in, principally, the Pyrobombus clade. Overall, monandry is the ancestral state for the eusocial corbiculate bees.

> The data do not allow us to determine whether monandry was already present in the solitary ancestors or whether monandry and eusociality evolved concurrently, but they are clearly linked.

Hughes, W. O., Oldroyd, B. P., Beekman, M., & Ratnieks, F. L. (2008). Ancestral monogamy shows kin selection is key to the evolution of eusociality. Science, 320(5880), 1213-1216.

The study is a good example of deductive reasoning. We simple cannot know what ancestral forms of honey bee were like, but using the species that exist today, we can see that the majority of them are monandrous, and that polyandry arose independently in a small number of branches on the ancestral tree, which is predates the division of hymenoptera into bees, wasps, and ants. It is an interesting question as to whether multiple mating evolved in conjunction with the formation of caste based colonies, but again, this happened many millions of years ago and all we have to go on is a few fossils, plus the examples of living species.

PLB

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