title: Egg-laying "intermorphs" in the ant Crematogaster smithi neither affect sexual production nor male parentage.
abstract: We study male parentage and between-colony variation in sex allocation and sexual production in the desert ant Crematogaster smithi, which usually has only one singly-mated queen per nest. Colonies of this species are known to temporarily store nutrients in the large fat body of intermorphs, a specialized female caste intermediate in morphology between queens and workers. Intermorphs repackage at least part of this fat into consumable but viable male-destined eggs. If these eggs sometimes develop instead of being eaten, intermorphs will be reproductive competitors of the queen but--due to relatedness asymmetries--allies of their sister worker. Using genetic markers we found a considerable proportion of non-queen sons in some, but not all, colonies. Even though intermorphs produce ∼1.7× more eggs than workers, their share in the parentage of adult males is estimated to be negligible due to their small number compared to workers. Furthermore, neither colony-level sex allocation nor overall sexual production was correlated with intermorph occurrence or number. We conclude that intermorph-laid eggs typically do not survive and that the storage of nutrients and their redistribution as eggs by intermorphs is effectively altruistic.
authors.affiliation: Biologie I, Universität Regensburg, Regensburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Oettler
authors.forename: Michiel B
authors.initials: MB
authors.lastname: Dijkstra
authors.forename: Jürgen
authors.initials: J
authors.lastname: Heinze
mesh_terms: D000818:Animals; D001000:Ants / Q000502:physiology*; D005260:Female; D008297:Male; D010058:Oviposition / Q000502:physiology; D012098:Reproduction / Q000502:physiology; D012726:Sexual Behavior, Animal / Q000502:physiology