Sexual reproduction by both queens and workers in the ponerine ant Harpegnathos saltator

Abstract

Ant workers are very often reproductively degenerate females, but in some species from subfamily Ponerinae, the workers can mate and lay fertilized eggs just like queens (they are then termed "gamergates"). In Harpegnathos saltator, new colonies are founded independently by single queens, and when senescent they are replaced by several gamergates. This secondary polygyny is distinguished by three features: (1) behavioural data indicate that young workers copulate with their brothers, unlike the queens who disperse and mate outside the nests; (2) gamergate colonies produce both male and female sexuals annually; (3) gamergate colonies appear not to fission. Our evidence for the lack of fission is indirect: the nests of H. saltator are unusually elaborate for ponerine ants, and gamergate colonies produce many young queens (at the expense of investing in workers). Queen supersedure results in an extension of colony lifespan, thus making complex constructions possible with a small colony size (65 ± 40 workers in a western Ghats population; N = 59). In turn, these nests represent a valuable resource to be inherited by successive generations of worker offspring. This life history contrasts with that of other ponerine ants having both queens and gamergates (e.g. in Rhytidoponera confusa, nests are simple and short-lived, gamergates are not inbred and their colonies can fission while producing mostly males; Ward, 1981 a, 1983 a).