These more aggressive, Africanized bees (so-called killer bees) received a lot of media attention in the U.S. as they moved north from South America. According to the U.S. Department of Agriculture, the first Africanized honey bees appeared in Texas in 1990. In less than a decade they had also spread to southern California, Arizona, Nevada and New Mexico.
Whitfield and Zayed wanted to understand the evolutionary mechanism that allowed the African honey bees to move into these new territories and dominate the bees that had arrived in the New World centuries earlier from eastern and western Europe.
Their analysis of about 440 SNPs selected randomly from throughout the Africanized honey bee genome showed that most of the alleles were common to African honey bees. But of the alleles common to European bees, those found in functional parts of the genome (in genes) were showing up more frequently than those in nonfunctional regions (between genes).
We asked the question: Is hybridization an essentially random process? Zayed said. When the African honey bees mated with the western European honey bees that had been in South America for centuries, one might expect that the hybrid offspring would randomly pick up both the functional and nonfunctional parts of the genome, he said.
But actually what we found was there was a preference for picking up functional parts of the western European genome over the nonfunctional parts.
It appeared that the Africanized bees that kept some of the functional western European genes were gaining an advantage, Whitfield said.
|Contact: Diana Yates|
University of Illinois at Urbana-Champaign