title: Reproductive competition triggers mass eviction in cooperative banded mongooses.
abstract: In many vertebrate societies, forced eviction of group members is an important determinant of population structure, but little is known about what triggers eviction. Three main explanations are: (i) the reproductive competition hypothesis, (ii) the coercion of cooperation hypothesis, and (iii) the adaptive forced dispersal hypothesis. The last hypothesis proposes that dominant individuals use eviction as an adaptive strategy to propagate copies of their alleles through a highly structured population. We tested these hypotheses as explanations for eviction in cooperatively breeding banded mongooses (Mungos mungo), using a 16-year dataset on life history, behaviour and relatedness. In this species, groups of females, or mixed-sex groups, are periodically evicted en masse. Our evidence suggests that reproductive competition is the main ultimate trigger for eviction for both sexes. We find little evidence that mass eviction is used to coerce helping, or as a mechanism to force dispersal of relatives into the population. Eviction of females changes the landscape of reproductive competition for remaining males, which may explain why males are evicted alongside females. Our results show that the consequences of resolving within-group conflict resonate through groups and populations to affect population structure, with important implications for social evolution.
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK f.j.thompson@exeter.ac.uk.
authors.forename: Faye J
authors.identifier: http://orcid.org/0000-0001-7581-2204
authors.initials: FJ
authors.lastname: Thompson
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.
authors.forename: Harry H
authors.identifier: http://orcid.org/0000-0003-2120-243X
authors.initials: HH
authors.lastname: Marshall
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Sanderson
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.
authors.forename: Emma I K
authors.initials: EI
authors.lastname: Vitikainen
authors.affiliation: School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK.
authors.forename: Hazel J
authors.identifier: http://orcid.org/0000-0002-4455-6065
authors.initials: HJ
authors.lastname: Nichols
authors.affiliation: School of Life Sciences, Napier University, Edinburgh EH10 5DT, UK.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Gilchrist
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Young
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Hodge
authors.affiliation: Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE, UK.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Cant
mesh_terms: D000818:Animals; D005260:Female; D008988:Herpestidae / Q000502:physiology*; D008297:Male; D012098:Reproduction; D012919:Social Behavior; D014454:Uganda
keywords: coercion; conflict; cooperation; eviction; forced dispersal; reproductive competition