Asexual, all-female termite colonies found to do just fine without males
Some species of termites have been known to reproduce asexually on occasion, but most of the time they seem to do things the old fashioned way. But nature, always looking for more efficient ways to get from A to B, may be in the process of trimming away some unnecessary steps in the process – namely, males. Researchers have now found colonies with no male termites at all, and they seem to be thriving.
Unlike other colony insects, like ants and bees which are basically all female, termites generally have a mix of both sexes. At the top of the chain is a queen and king pair, who get busy to produce the thousands of workers that make up the population. But interestingly, a few years ago a study found that while the workers are born out of the two-player termite tango, queens can also ditch the king and reproduce new queens asexually.
But the extent of asexual reproduction in termites wasn't understood. In the new work, the researchers examined 10 populations of a Japanese species known as Glyptotermes nakajimai, and were surprised to find that six of these colonies were made up entirely of asexual females.
On closer inspection, the team found that this wasn't just a case of lingering male influence, either. The queens of these colonies had no sperm stored up from previous encounters, and their eggs were unfertilized. Importantly, the hatching rate of those unfertilized eggs were no worse off than fertilized eggs in mixed-sex colonies, raising the question of what purpose males serve in these communities.
"These results demonstrate males are not essential for the maintenance of animal societies in which they previously played an active social role," says Nathan Lo, an author of the study.
The researchers say that this all-girls club could be an evolutionary adaptation. Even sexually reproducing species occasionally churn out babies from unfertilized eggs, and this could have led to the fully asexual populations over time. The team managed to trace back the genetic history of these asexual colonies to 14 million years ago, when they last split from sexual species.
While most of us would need a pretty good reason to give up sex, according to the researchers abstaining has helped the colonies adapt to new environments better. They also seem to be more efficient at defending the colony, with a more uniform head size and fewer soldiers compared to other groups. And to top it all off, with the "fat" trimmed away the colonies may be able to spread better.
"All else being equal, asexual populations grow at twice the rate of sexual populations because only females are required to reproduce," says Lo. "This increased growth rate of colonies makes it easier for populations to entrench themselves in new environments."
Termites aren't the only species to have eschewed sex. In recent years, studies have looked at this kind of behavior in parasitic worms, salamanders, cockroaches, crayfish, and leopard sharks – and across the board, creatures that kept it in their pants were always better off than those who got their freak on.
The research was published in the journal BMC Biology.
Source: University of Sydney