KIN‐BASED RECOGNITION AND SOCIAL AGGREGATION IN A CILIATE |
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Authors: | Alexis S. Chaine Nicolas Schtickzelle Thierry Polard Michèle Huet Jean Clobert |
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Affiliation: | 1. Station d’Ecologie Expérimentale du CNRS à Moulis USR2936, 09200 Saint‐Girons, France;2. E‐mail: alexis.chaine@ecoex‐moulis.cnrs.fr;3. Biodiversity Research Centre, Université catholique de Louvain, Croix du Sud 4, 1348 Louvain‐la‐Neuve, Belgium;4. E‐mail: nicolas.schtickzelle@uclouvain.be;5. E‐mail: thierry.polard@gmail.com;6. Current address: Laboratoire d’Ecologie Fonctionelle UMR 5245, Avenue de l’Agrobiopole BP 32607, 31326 Castanet‐Tolosan, France;7. E‐mail: michelle.huet@ecoex‐moulis.cnrs.fr;8. E‐mail: jean.clobert@ecoex‐moulis.cnrs.fr |
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Abstract: | Aggregative groups entail costs that must be overcome for the evolution of complex social interactions. Understanding the mechanisms that allow aggregations to form and restrict costs of cheating can provide a resolution to the instability of social evolution. Aggregation in Tetrahymena thermophila is associated with costs of reduced growth and benefits of improved survival through “growth factor” exchange. We investigated what mechanisms contribute to stable cooperative aggregation in the face of potential exploitation by less‐cooperative lines using experimental microcosms. We found that kin recognition modulates aggregative behavior to exclude cheaters from social interactions. Long‐distance kin recognition across patches modulates social structure by allowing recruitment of kin in aggregative lines and repulsion in asocial lines. Although previous studies have shown a clear benefit to social aggregation at low population densities, we found that social aggregation has very different effects at higher densities. Lower growth rates are a cost of aggregation, but also present potential benefits when restricted to kin aggregations: slow growth and crowd tolerance allow aggregations to form and permit longer persistence on ephemeral resources. Thus in highly dynamic metapopulations, kin recognition plays an important role in the formation and stability of social groups that increase persistence through cooperative consumptive restraint. |
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Keywords: | Cooperation dispersal kin recognition phenotype‐dependent dispersal social aggregation social evolution Tetrahymena thermophila |
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