Same-sex Pairs Retain Their Reproductive Capacity as a Potential Opportunity for Individual Reproductive Success in Termites

Abstract

In eusocial termites, successful pairing is an essential element of dispersal and distribution after the departure of alates from natal colonies. Two situations could arise during the pairing process: mixed-sex pairs and same-sex pairs. However, most previous studies focused on mixed-sex pairs, overlooking groups formed by same-sex pairings, especially potential fecundity (the total number of oocytes or ovarioles), oogenesis and the development stage of oocytes of females in female–female pairs, and spermatogenesis and testis development of males in male–male pairs. In this study, through experimentation, we investigated the reproductive ability of virgin dealates based on various pairing types as mentioned above. We found that the life spans of virgin dealates can cover 1 yr or even more when they establish a nest with a partner, which is more than 10-fold longer than the life span of individuals establishing a colony alone. After 1 yr of pairing, the potential fecundity of virgin same sex dealates did not degenerate significantly compared with newly emerged dealates, including the number of ovarioles, size of testis, oogenesis, and the development stage of the oocytes. Moreover, when individuals of same-sex pairings experimentally changed into mixed-sex pairs after 1 yr, the eggs produced in the colony hatched into larvae. These findings suggest that dealates which through same-sex pairs retain fecundity after 1 yr have more reproductive potential than dealates that failed to pair with heterosexuals, shedding light on the ecological significance of homosexual behaviors in terms of the successful extension and fecundity of eusocial termites.

The strength of sexual signals predicts same-sex paring in termites

“…By comparing with other termite lineages, our results suggest that the same-sex tandems in Coptotermes termites are not functional behaviors but could exist because they inherited them from the ancestral state of termite tandem running behavior [11], as in the framework of the previous work [4]. Previous studies on same-sex tandem runs in termites have focused only on Reticulitermes termites [11,12,25,26], which belong to the same family as Coptotermes. In Reticulitermes termites, same-sex pairing functions by providing survival benefits [5,12,27] and is not a result of mistaken identity [11].…”