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Promiscuous Queen Bees Maintain Genetic Diversity in Island Environment
By mating with nearly 100 males, queen bees on isolated islands avoid inbreeding and keep colonies healthy. The results, published online in PLoS ONE, focused on giant honey bee colonies on Hainan Island, off the coast of China. Because these bees have long been separated from their continental cousins, it was thought that the island bees would be prime candidates for inbreeding as well as having very different genes, said Dr. Zachary Huang, Michigan State University (MSU) entomologist. “We believed that the island bees would show evidence of the founder effect, or random genetic changes in an isolated population, on a unique sex determination gene from the mainland bees,” he said. “At first we were surprised when we couldn’t document this effect. Looking at it further, I asked myself, ‘Why didn’t I think of this before?’” When compared to bees, humans have a rather simplistic sex-determination process. In females, the two sex-determination chromosomes are the same, and in males the two chromosomes are different. With bees, however, the combinations of complementary sex determination genes, or CSDs, determine the sex and the societal role of the bees. One particular gene can have alleles – the “flavor” of genes. In humans, they dictate hair and eye color. In bees, though, they are responsible for creating females (worker bees), fertile males (that mate with the queen) or infertile males (diploid males which serve no purpose). The “voila” moment came once Dr. Huang estimated the bees’ mating habits and the potential of CSD allele combinations. That’s when he understood why he couldn’t confirm the founder effect. Keeping the CSD mix diverse is one of the keys to maintaining a healthy hive, he said. The island queens carry around 40 CSD alleles.