title: Does cooperation mean kinship between spatially discrete ant nests?
abstract: Eusociality is one of the most complex forms of social organization, characterized by cooperative and reproductive units termed colonies. Altruistic behavior of workers within colonies is explained by inclusive fitness, with indirect fitness benefits accrued by helping kin. Members of a social insect colony are expected to be more closely related to one another than they are to other conspecifics. In many social insects, the colony can extend to multiple socially connected but spatially separate nests (polydomy). Social connections, such as trails between nests, promote cooperation and resource exchange, and we predict that workers from socially connected nests will have higher internest relatedness than those from socially unconnected, and noncooperating, nests. We measure social connections, resource exchange, and internest genetic relatedness in the polydomous wood antFormica lugubristo test whether (1) socially connected but spatially separate nests cooperate, and (2) high internest relatedness is the underlying driver of this cooperation. Our results show that socially connected nests exhibit movement of workers and resources, which suggests they do cooperate, whereas unconnected nests do not. However, we find no difference in internest genetic relatedness between socially connected and unconnected nest pairs, both show high kinship. Our results suggest that neighboring pairs of connected nests show a social and cooperative distinction, but no genetic distinction. We hypothesize that the loss of a social connection may initiate ecological divergence within colonies. Genetic divergence between neighboring nests may build up only later, as a consequence rather than a cause of colony separation.
authors.affiliation: York Centre for Complex Systems Analysis & Department of Biology University of York York UK; Centre for Exercise, Nutrition and Health Sciences School for Policy Studies University of Bristol Bristol UK.
authors.forename: Duncan S
authors.identifier: 0000-0003-1874-1205
authors.initials: DS
authors.lastname: Procter
authors.affiliation: Forest Research Roslin Midlothian UK.
authors.forename: Joan E
authors.initials: JE
authors.lastname: Cottrell
authors.affiliation: Forest Research Farnham Surrey UK.
authors.forename: Kevin
authors.initials: K
authors.lastname: Watts
authors.affiliation: Forest Research Roslin Midlothian UK.
authors.forename: Stuart W
authors.initials: SW
authors.lastname: A'Hara
authors.affiliation: Institut für Biochemie und Biologie Universität Potsdam Potsdam Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Hofreiter
authors.affiliation: York Centre for Complex Systems Analysis & Department of Biology University of York York UK.
authors.forename: Elva J H
authors.initials: EJ
authors.lastname: Robinson
keywords: Formica lugubris; colony organization; eusociality; kin selection; polydomy; social organization