A putatively new ant species from the Cataglyphis cursor group displays low levels of polyandry with standard sexual reproduction

Abstract

How social organisation (number of queens and mating partners) and reproductive systems (use of thelytoky vs sex) evolved in ants and how they interplay is still far from clear. The Cataglyphis desert ants represent a fascinating group as it harbours variation in both levels of polyandry and the use of thelytoky, with polyandry and sexual reproduction probably being the ancestral state. In this study, we compared the colony and population genetic structure of two populations of the Cataglyphis cursor group distributed in a remote small geographic area in central Spain with those of their geographically closest species C. piliscapa and C. cursor. Not surprisingly, we found that the two populations are genetically isolated from those of C. piliscapa and C. cursor, both for the mtDNA and microsatellite markers. Interestingly, we observed a lower level of polyandry in the C. cursor from Spain even though the population genetic diversity was like C. piliscapa and C. cursor. Queens did not appear to use frequently thelytoky which supports the hypotheses that low levels of polyandry disfavours the use of thelytoky. Reversion to a lower level of polyandry has rarely been observed in ants, and we discuss multiple hypotheses that could explain this phenomenon. Whether these remote populations belong to a putatively new species requires a careful taxonomic investigation. Our study highlights the lability of the reproductive system in this group and provides an exciting system to investigate the coevolution of polyandry and thelytoky.