Japanese male and female termites have very sex-specific courtship behaviors known as tandem runs that mark the beginning of a new colony. It turns out that same-sex pairings of the same species also perform tandem runs, and members of these same-sex pairings can express the behavior of the opposite sex, delivering the same pair coordination seen in their heterosexual counterparts.
"The tandem run is highly coordinated, with each sex showing a distinct behavior," lead author Dr. Nobuaki Mizumoto, from Okinawa Institute of Science and Technology, said in a statement. "The female termite always leads the way, and the male termite always follows close behind. If they get separated, the female pauses while the male searches for her."
The team was intrigued to see if and how such behavior would happen in same-sex pairings. Termites pair up not just for reproduction, but also to groom each other and stay healthy. A quick pairing is also advantageous as it reduces the chance of being preyed upon. So, being open to all sexes seems like a good survival strategy, even more so due to the fact that female termites can choose to reproduce via parthenogenesis, without the need for a male.
The tandem runs in opposite- and same-sex pairings showed similar dynamics. In female-female pairs, there was a female leader and a female follower. When the two were separated, the follower searched for the leader, something that in heterosexual pairings is a typical male trait. Equally in male-male pairings, the male leader would stop and wait if the pair got split up. That’s a typical female trait in heterosexual pairings.
Computer simulation showed that if termites in same-sex pairings were restricted to their heterosexual sex role, they would either be less likely to be reunited or it would take a much longer time.
The team originally wondered if the driver of same-sex behavior in termites was due to indiscriminate mating, but the evidence here suggests that the termites alter their behavior when in same-sex pairings. All termite species in the Neoisoptera group – including this Japanese termite – have female-led tandem runs, but more distantly related species have tandem runs that can be led by either males or females.
"This suggests that male and female termites that were the ancestors of modern termites likely had the ability to both lead and follow. That could be why the potential for females and males to switch behaviors still exists in modern termites, allowing same-sex pairings to evolve," explained Dr. Mizumoto.
The study was published in Proceedings of the National Academy of Sciences.