The researchers, University of Illinois entomology professor Charles Whitfield and postdoctoral researcher Amro Zayed, analyzed specific markers of change in the genes of honey bees in Africa, Europe, Asia, and the Americas. They also focused on geographic regions – such as Brazil in South America – where multiple honey bee invasions had occurred.
The researchers were looking for tiny variations in the sequences of nucleotides that make up all genes. Certain versions of these single nucleotide polymorphisms (SNPs, or “snips”) are more common to African honey bees, while others occur more frequently in honey bees in western Europe, eastern Europe, or Asia.
By comparing these SNPs in bees from different geographic territories, and by looking at the frequency at which particular alleles, or variants, occur in functional and nonfunctional parts of the honey bee genome, the researchers were able to determine that the invading bees were not just randomly acquiring genetic material from their predecessors by interbreeding with them, but that certain genes from the previously introduced bees were giving the newcomers an advantage.
An earlier study led by Whitfield and published in Science in 2006 showed that A. mellifera originated in Africa and not Asia, as some had previously hypothesized.
That study revealed that the honey bee had expanded its territory into Eurasia at least twice, resulting in populations in eastern and western Europe that were quite different from one another.
The earlier analysis also confirmed and extended results of previous studies showing that African honey bees had mixed with but largely displaced their predecessors in the New World, which were primarily of western European stock. When the European old-timers mixed with the African newcomers, their offspring looked, and in most respects behaved, like the African honey bees.
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.”
“Those African bees are doing better because there were western European honey bees there for them to mix with,” he said. “Now we can say we have a signature for evolution in the genome.”
While the researchers do not yet know how these European honey bee genes are enhancing the survival and fitness of the Africanized bees in the Americas, Whitfield said, it may be that specific traits from western Europe are beneficial, or it may be that being a hybrid is, in and of itself, a good thing for these bees.
In a separate finding, the researchers also discovered a genomewide signature of evolution associated with the ancient expansion of honey bees from Africa into temperate regions of western and northern Europe. In this expansion, functional parts of the genome have changed more than nonfunctional parts. Whitfield thinks that these changes may involve social adaptations to survive the hard winters.
“The way the honey bees survive in temperate regions is sort of the way humans do,” Whitfield said. “They have a shelter. They store resources.”
Not needing to survive in such cold weather, African bees store less food and reproduce more.
“So how does an animal that’s basically tropical make it? How does it expand its territory and thrive in very harsh winter conditions in this temperate region?” Whitfield asked. “Humans did it, and Apis mellifera did it in some interestingly parallel ways.”
Whitfield is also an affiliate of the Institute for Genomic Biology.
Diana Yates | University of Illinois
The Secret of the Rock Drawings
24.05.2019 | Max-Planck-Institut für Chemie
Chemical juggling with three particles
24.05.2019 | Rheinische Friedrich-Wilhelms-Universität Bonn
A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.
The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...
Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.
The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...
Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...
With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.
Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...
'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.
However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...
29.04.2019 | Event News
17.04.2019 | Event News
15.04.2019 | Event News
27.05.2019 | Information Technology
24.05.2019 | Physics and Astronomy
24.05.2019 | Medical Engineering