Selon la theorie de la selection de la parentele, les individus peuvent transmettre des copies de leurs genes a la generation suivante sans acceder eux-memes a la reproduction, mais en aidant des apparentes a augmenter leur propre succes reproductif. Ce concept reste aujourd'hui l'explication la plus probable pour justifier l'evolution de l’altruisme de reproduction dans le regne animal. Les coefficients de correlations genetiques entre les membres d’un groupe ont une importance capitale, puisqu'ils influencent directement les benefices genetiques indirects associes au comportement altruiste. Trois principaux facteurs sont cependant connus pour influencer profondement l'architecture des societes: (i) le nombre de reines presentes dans un nid (polygynie), (ii) le nombre d'accouplements des reines (polyandrie), et (iii) l’accouplement entre apparentes (consanguinite).

Nestmate recognition cues can derive from genetic and/ or environmental factors and can be context-dependent rather than fixed over time. We examined the influence of genetic relatedness and environment on nestmate recognition and its seasonal variations in a natural population of the polydomous ( multiple- nests per colony) ant Plagiolepis pygmaea in southern France. Recognition between colonies was measured by testing aggression levels during encounters between five workers of colony A and one of colony B and vice versa. The combination of genetic data, spatial data and aggressive behaviour data shows that nestmate recognition cues have principally a genetic component. Whereas workers from different nests of the same colony are never aggressive to each other, they are always hostile to alien conspecifics regardless of the spatial or genetic distance between the colonies. Our results also reveal significant seasonal variations in the levels of aggression among workers of different colonies, probably according to the biological cycles of the species. Surprisingly, despite the mode of colony reproduction being budding in P. pygmaea, the population of Tarabel is not genetically structured.