The Amazons dreamed about it, but termites have actually done it! That is to say living and prospering in exclusively female groups... In a study published in the BMC Biology journal, researchers revealed the existence of colonies of a species of this family of insects in Japan, called Glyptotermes nakajimai, in which there are no males.
Colonies where the females are completely self-sufficient is quite common in some insects. Bees and ants are perfect examples; they form colonies entirely composed of females, the males’ role being only to fertilise the queen from time to time. But in termites, their mannerisms are usually quite different.
For a majority of these members of the blattodea order, parity is indeed in the heart of the colonies, composed equally of asexual males and females, the workers, who devote themselves to their queen, but also their king, the role being to ensure the continuation of the group.
Mixed-sex, a principle foreign to most of the colonies studied
However, it was a very different mode of organisation that Australian and Japanese researchers were surprised to discover when studying Japanese specimens. By carefully listing each of the individuals of 74 colonies spread over fifteen sites across the Japanese archipelago, scientists had indeed found that no less than 60% of colonies were devoid of any male representative.
Although this is surprising, this absence seems to have no consequence on the prosperity of these exclusively feminine termites. Australian researchers have also been studying the reproductive mechanisms of these unusual termite colonies. While when it comes to their counterparts the queen retains some of the royal sperm in a storage organ, for exclusively female colonies this reserve has proven to be completely empty.
As a result, the queen produces non-fertilised eggs. Not fertilised but not free of life however, quite on the contrary! After incubation, these eggs hatch at the same rate as those of mixed colonies. This is due to asexual reproduction known as parthenogenesis.
The males, non-essential beings
Although parthenogenesis has already been observed in animals such as sharks, snakes or amphibians, this discovery opens new perspectives on a better understanding of asexual reproduction processes, as explained by evolutionary biologist Nathan Lo at the University of Sydney. ‘These results demonstrate that males are not essential for the maintenance of animal societies in which they previously [had] played an active social role.’
According to the researchers, the differentiation between the two forms of settlement organisation appears to have occurred about 14 million years ago. This estimate came from the genetic analysis of the different groups of termites. The absence of a male certainly does not seem to affect the prosperity of the colonies, quite on the contrary. ‘All things being equal, asexual populations grow twice as fast as sexual populations, because only females are needed for reproduction,’ says Lo.
‘This increase in colony growth rates makes it easier for the population to settle in new environments,’ says the biologist. This theory was confirmed by the location of exclusively female colonies discovered by researchers.
The colonies are isolated to the islands of Shikoku and Kyushu, south of the Japanese archipelago. This exile is not without consequences on their morphological and societal characteristics.
According to the researchers, members of exclusively female colonies have greater homogeneity when it comes to the size of their heads, as well as a smaller proportion of termites responsible for the defence of the group. These differences may correspond to the current appearance of a brand new species, which is a palpable testimony of the action of evolutionary processes.
‘Our findings show that completely asexual social lines can evolve from mixed termite societies,’ the scientists say in their publication. The myth of the Amazons may have predicted it, but Japanese termites are now proof that an all-female community can exist!