Fecundity determines the outcome of founding queen associations in ants

Animal cooperation evolved because of its benefits to the cooperators. Pleometrosis in ants—the cooperation of queens to found a colony—benefits colony growth, but also incurs costs for some of the cooperators because only one queen usually survives the association. While several traits in queens influence queen survival, they tend to be confounded and it is unclear which factor specifically determines the outcome of pleometrosis. In this study, we used the ant Lasius niger to monitor offspring production in colonies founded by one or two queens. Then, we experimentally paired queens that differed in fecundity but not in size, and vice versa, to disentangle the effect of these factors on queen survival. Finally, we investigated how fecundity and size differed between queens depending on whether they were chosen as pleometrotic partners. Our results indicate that pleometrosis increased and accelerated worker production via a nutritional boost to the larvae. The most fecund queens more frequently survived the associations, even when controlling for size and worker parentage, and queens selected as pleometrotic partners were less fecund. Our results are consistent with fecundity being central to the onset and outcome of pleometrosis, a classic example of cooperation among unrelated animals.

Fecundity determines the outcome of founding queen associations in ants

Animal cooperation evolved because of its benefits to the cooperators. Pleometrosis in ants - the cooperation of queens to found a colony - benefits colony growth, but also incurs costs for some of the cooperators because only one queen usually survives the association. While several traits are associated with queen survival, they tend to be confounded and it is unclear which factor specifically determines the outcome of pleometrosis. In this study, we used the ant Lasius niger to monitor offspring production in colonies founded by one or two queens. Then, we experimentally paired queens that differed in fecundity but not in size, and vice versa, to disentangle the effect of these factors on queen survival. Finally, we investigated how fecundity and size differed between queens depending on whether they were chosen as pleometrotic partners. Our results indicate that pleometrosis increased and accelerated worker production via a nutritional boost to the larvae. The most fecund queens more frequently survived the associations, even when controlling for size and worker parentage, and queens selected as pleometrotic partners were less fecund. Our results are consistent with fecundity being central to the onset and outcome of pleometrosis, a typical case of cooperation among unrelated animals.

Natural History of the AntPheidole desertorumWheeler in a Desert Grassland Habitat

Pheidole desertorumcolonies are large for the genus; the number of adult workers in established colonies ranges from 2,460–24,814. They are nocturnal during summer and are predators and scavengers on arthropods. Both minor and major workers forage, although foraging by majors appears to occur primarily when food is abundant. Young major workers may function as repletes. The adult major/minor worker ratio varies greatly among colonies; much of that variance appears explained by colony size and marturity of adult colony reproductive broods. Most colonies produce reproductives each year and colony sex ratios are extremely sex-biased. Mating season begins following summer rainfall, Males and gynes fly prior to sunrise; males form aerial swarms which gynes enter. Mating occurs on the ground, then gynes fly awy, presumably o suitable colony founding sites Colony f0udation is normally haplometrotic, although pleometrotic queen associations with workers are found.