Special genes allow an isolated honeybee population to reproduce asexually. Unlike other bee populations, these honeybees can survive without males.
In the normal scheme of things, a majority of animals reproduce sexually, a process that requires a male and a female. In the bee world, a female queen bee reproduces using the sperm from male drones.
But one honeybee population found in South Africa evolved to help them reproduce and survive without the help of male bees. The female Cape bees (Apis mellifera capensis) can lay eggs that are already fertilized using their own DNA.
But that's not all. These Cape bees are also capable of invading other bees' nests and rule their world by reproducing in the same fashion. Scientists call the behavior "social parasitism."
Scientists from the Uppsala University in Sweden looked into the genetic mechanisms that enable Cape bees to reproduce asexually and why they exhibit the unique behavior.
They discovered significant differences in the genes of the Cape bees and other African honeybee populations. The gene variations could explain both the odd parasitic behavior and the asexual reproduction.
While the genomes of the Cape bees and other African honeybees are somewhat similar, there were 39 areas in the parasitic bees' genomes that are different from the rest.
This suggests that social parasitism requires multiple genes. Some of the required genes may involve the ones that play roles in hormonal signaling, which makes the Cape bees activate their ovaries.
It can also involve some of the genes that are part of the sex cells' chromosomal segregation, which could have caused the Cape bees to switch toward a different method of reproduction.
"We don't know what these different genes are doing and how they cause this behavior, but we can see there are definitely strong signals of something different going on there," said Matthew Webster from Uppsala University's Department of Medical Biochemistry and Microbiology.
How the Cape bees evolved into having an odd way of reproducing remains a mystery. However, by analyzing the involved genes, the scientific community is one step closer to understanding it. The study can also help shed new light into how genes control behavior and cell division.
"Furthermore, understanding why populations sometimes reproduce asexually may help us to understand the evolutionary advantage of sex, which is a major conundrum for evolutionary biologists," added Webster.
The findings were published in the journal PLOS Genetics on June 9.