> >I'm sure I "knew" that the sperm from different drones was homogeneously mixed in the spermatheca - doesn't this mitigate against this?
> Depends upon how well the homogenization is done.  There is no mechanical mixer.

After discarding unwanted ejaculates, queens might in fact not favor any specific male but try to equalize the contributions from their mates, independently of how much sperm each male contributed. The reason to perform such “genotype scrambling” is that this results in a general increase in genetic diversity among worker offspring (see also Boomsma and Ratnieks, 1996). As mentioned earlier this has repeatedly been shown to benefit colony performance in various different ways.

Further support for the “genotype scrambling” hypothesis comes from studies of patriline distributions in honeybee colonies. As Schlüns et al. (2005) show, patrilines are relatively evenly distributed in seven honeybee species investigated, at least for the most frequent patrilines, and no patriline is able to monopolize paternity in the ways expected from last or first male precedence.

The fact that patrilines are rather evenly distributed in honeybee worker offspring thus supports the idea that females might indeed try to equalize male contributions during the sperm storage process. Experiments where queens were serially inseminated with sperm from different males also support active equalizing of sperm contributions by queens, as the order of injection had no or only a weak effect upon the success of ejaculates in siring worker offspring (Laidlaw and Page, 1984; Schlüns et al., 2004; Moritz, 1986). 

Boris Baer. Sexual selection in Apis bees. Apidologie, Springer Verlag, 2005, 36 (2), pp.187-200.

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html