title: Major Hurdles for the Evolution of Sociality.
abstract: Why do most animals live solitarily, while complex social life is restricted to a few cooperatively breeding vertebrates and social insects? Here, we synthesize concepts and theories in social evolution and discuss its underlying ecological causes. Social evolution can be partitioned into (a) formation of stable social groups, (b) evolution of helping, and (c) transition to a new evolutionary level. Stable social groups rarely evolve due to competition over food and/or reproduction. Food competition is overcome in social insects with central-place foraging or bonanza-type food resources, whereas competition over reproduction commonly occurs because staying individuals are rarely sterile. Hence, the evolution of helping is shaped by direct and indirect fitness options and helping is only altruism if it reduces the helper's direct fitness. The helper's capability to gain direct fitness also creates within-colony conflict. This prevents transition to a new evolutionary level.
authors.affiliation: Department of Evolutionary Biology & Ecology, University of Freiburg, D-79104 Freiburg, Germany; email: judith.korb@biologie.uni-freiburg.de.
authors.forename: Judith
authors.initials: J
authors.lastname: Korb
authors.affiliation: Institute of Zoology/Evolutionary Biology, University of Regensburg, D-93040 Regensburg, Germany; email: juergen.heinze@biologie.uni-regensburg.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Heinze
mesh_terms: D000818:Animals; D005075:Biological Evolution; D007313:Insecta / Q000502:physiology*; D012919:Social Behavior; D014714:Vertebrates / Q000502:physiology
keywords: competition; conflict; inclusive fitness; reproductive conflict; social evolution; social insects