New Paper: Diploid males and female mating failures in ants, bees, and wasps

By , August 10, 2012

Happy to announce a new paper by the Zayed lab, just published by Entomologia Experimentalis et Applicata.  The paper is an invited review on how the production of diploid males in ants/bees/wasps can cause female mating failures.  It was authored by Brock Harpur (MSc candidate), and Mona Sobhani (undergraduate honours thesis student).

A mating between a male and female that share the same version of the sex-determining genes (here ‘a’). Half of the female’s fertilized eggs will be ‘a,a’ and will develop into diploid males. This is Fig. 1 from Zayed A, Packer L (2005) Complementary sex determination substantially increases extinction proneness of haplodiploid populations. Proceedings of the National Academy of Sciences of the United States of America 102, 10742-10746.

Sex in many ants, bees, and wasps is determined by the combination of alleles at one (but sometimes two or more) gene.  Females arise from fertilized eggs and have two different ‘versions’ of the sex-determining gene.  Normally, males arise from unfertilized eggs and only have a single ‘version’ of the sex determining gene; these are normal ‘haploid’ males.  Sometimes – when there isn’t enough genetic diversity at the sex determining gene – zygotes can have two of the same ‘version’ of the sex-determining gene; this tricks the sex determination system into thinking that there is only one copy, and so a diploid male if produced.

For the paper, we reviewed the literature to learn more about the fate of these diploid males.  We found that diploid males often reach adulthood, and are often capable of mating with females.  However, diploid males in most species are effectively sterile and females mating with diploid males can not produce daughters of their own.  Even when diploid males are fertile, their mates produce an inferior number of daughters when compared to haploid males.

This is bad news for bee conservation genetics because diploid males have a much greater negative effect on population persistence when they are effectively sterile! [see the 2005 Zayed & Packer PNAS paper on this].

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