title: Haplodiploidy, sex-ratio adjustment, and eusociality.
abstract: Hamilton's "haplodiploidy hypothesis" holds that inflated sororal relatedness has promoted altruistic sib rearing in haplodiploids, potentially explaining their apparent predisposition to eusociality. Here, we suggest that haplodiploidy may instead promote eusociality simply by facilitating sex-ratio adjustment. Specifically, haplodiploidy may enable sex-ratio bias toward the more helpful sex, owing to "local resource enhancement," and such sex-ratio bias may promote the evolution of helping by individuals of that sex, owing to the "rarer-sex effect." This could explain why haplodiploidy appears to have been important for eusociality in taxa with only female helpers, such as ants, wasps, and bees, but not in taxa with both male and female helpers, such as termites.
authors: Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, United Kingdom. andy.gardner@zoo.ox.ac.uk
authors: Andy
authors: A
authors: Gardner
authors: Laura
authors: L
authors: Ross
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D005075:Biological Evolution; D004171:Diploidy; D005260:Female; D056084:Genetic Fitness / Q000235:genetics / Q000502:physiology; D006238:Haploidy; D006379:Helping Behavior; D007313:Insecta / Q000235:genetics / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D012744:Sex Ratio