Genetics 1
Bdna cropped
Gene Pools and Gene Flow

Honey bees spread their genes - gene flow - in two ways:
paternal gene flow occurs when a drone flies to mate with a queen from a distant colony;
maternal gene flow occurs when a queen and some of her workers swarm and fly to a new location.

Feral bees which lived in woods and forests provided an important gene store for the native bees. With swarming the bees were able to transfer their genes. Natural selection ensured that the best genes survived and that bees evolved to be strong and well adapted to their environment. But with the devastation brought on by varroa this source of genes has all but disappeared.

The hobbyist beekeeper with only a few colonies is now in charge of an isolated gene pool which in some rural areas could be called a gene island with no natural spread of the genes possible. Only the beekeeper can spread the genes by transferring queens, drones or colonies.
The Honeybee Genome Project

The genome for the honeybee was sequenced in 2006.
A very instructive 4 part video is given on the project by Nature.
A comprehensive summary of the findings of the project is available.

Information from the genome project has shown that honeybees posses an exceptionally high level of recombination- the process by which genetic material is mixed during reproduction - across the genome. This is thought to increase genetic diversity among honeybees where the queen is the only reproductive female.
But on the downside the project also discovered that the honeybee has fewer genes providing resistance towards disease that other insects. And the number of genes responsible for detoxification also appears to be smaller in the honeybee which would make it more sensitive to pesticides.
This space filling model of a very small part of the DNA molecule shows 12 base-pairs; the major and minor grove is readily seen.
260 million base pairs are found in each
DNA molecule.
In the genome project, the researchers report that the honeybee has evolved more slowly than the fruit fly or mosquito and contains 10 157 known genes.
Hygienic Behaviour

Bees, in common with a number of other social insects, have well developed behavioural responses to combat disease. These behavioural responses are collectively known as hygienic behavior and include recognition and removal of diseased brood by worker bees. Bee species, and even different hives of the same species, differ in their ability to perform hygienic behaviours, with some colonies far superior to others. Some strains of bees are capable of recognizing diseased brood well before it is a threat to the hive, and remove diseased individuals. In some cases, the task of disposing of disease insects falls to specialist 'undertaker bees' that appear to be old workers. Bees are also assisted in resisting disease by propolis, present in the plant resins collected by honey bees and used as a sealant in the hives. Propolis is known for its antimicrobial properties.

Hygienic behaviour is dependent on the genetic makeup of the colony. Honey bee genetics are looked at in the following pages.
The genetic make up of the colony

Wing vernation measurements can give some idea of the genetic makeup of the colony but the most obvious in my colonies is the variation in colour. Most of the bees are typically a dark brown with obvious banding between the tergites. However, some bees in each colony are jet black with little colour banding. These different subsets of bees giving evidence of the queen's mating with different drones.
Next page: Genetics 2.
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