Fine-scale habitat heterogeneity favours the coexistence of supergene-controlled social forms in Formica selysi

BMC Evolutionary Biology

article

Zahnd, Sacha¹  Fontcuberta, Amaranta¹  Koken, Mesut¹  Cardinaux, Aline¹  Chapuisat, Michel¹ 

[1] Department of Ecology and Evolution, University of Lausanne

关键词: Habitat heterogeneity;    Competition-colonization trade-off;    Supergenes;    Spatially varying selection;    Social polymorphism;    Queen number;    Ants;    Habitat saturation;   

DOI  :  10.1186/s12862-020-01742-0

学科分类：护理学

来源: BioMed Central

【 摘 要 】

Social insects vary widely in social organization, yet the genetical and ecological factors influencing this variation remain poorly known. In particular, whether spatially varying selection influences the maintenance of social polymorphisms in ants has been rarely investigated. To fill this gap, we examined whether fine-scale habitat heterogeneity contributes to the co-existence of alternative forms of social organization within populations. Single-queen colonies (monogyne social form) are generally associated with better colonization abilities, whereas multiple-queen colonies (polygyne social form) are predicted to be better competitors and monopolize saturated habitats. We hypothesize that each social form colonizes and thrives in distinct local habitats, as a result of their alternative dispersal and colony founding strategies. Here, we test this hypothesis in the Alpine silver ant, in which a supergene controls polymorphic social organization. Monogyne and polygyne colonies predominate in distinct habitats of the same population. The analysis of 59 sampling plots distributed across six habitats revealed that single-queen colonies mostly occupy unconnected habitats that were most likely reached by flight. This includes young habitats isolated by water and old habitats isolated by vegetation. In contrast, multiple-queen colonies were abundant in young, continuous and saturated habitats. Hence, alternative social forms colonize and monopolize distinct niches at a very local scale. Alternative social forms colonized and monopolized different local habitats, in accordance with differences in colonization and competition abilities. The monogyne social form displays a colonizer phenotype, by efficiently occupying empty habitats, while the polygyne social form exhibits a competitor phenotype, thriving in saturated habitats. The combination of the two phenotypes, coupled with fine-scale habitat heterogeneity, may allow the coexistence of alternative social forms within populations. Overall, these results suggest that spatially varying selection may be one of the mechanisms contributing to the maintenance of genetic polymorphisms in social organization.

【 授权许可】

CC BY|CC0