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Nature of a Greenbeard Gene in the Fire Ant

Project description

Insights into the evolutionary mechanisms of social behaviour

Theory predicts that altruistic behaviours should occur only among related individuals. Surprisingly, the so-called Green-beard effect lead genetically unrelated individuals to cooperate as long as they share the same cooperation locus. The key objective of the EU-funded GreenAnt project is to study a Green-beard genetic element – the Social b supergene – in the fire ant, where carriers kill non-bearer queens. Researchers are interested to understand the genetic basis of the Green-beard effect in this species, and how it is maintained and spread. Results will provide fundamental insight into the evolutionary mechanisms of social behaviour.


Greenbeard genes are selfish genetic elements (SGEs) that favor their own transmission by increasing the fitness of other carrying individuals. Such a phenotype, can only occur if a gene or a group of tightly linked genes produce (1) a conspicuous phenotype, (2) the ability to recognize this phenotype, allowing the bearer individual to discriminate carriers from non-carriers and (3) a nepotistic behavior in favor of carriers. These extraordinary SGEs can have profound evolutionary consequences on genomes and social behavior. The first identified Greenbeard haplotype was in the fire ant Solenopsis invicta. In this species, the Social b (Sb) supergene, an 11 Mb non-recombining region is associated with a Greenbeard effect. Discriminating on cuticular chemical profiles, carrier ant workers spread the Sb supergene by killing non-bearer queens. In this project I aim to identify the genetic basis of the queen-discrimination ability of Greenbeard-carrier ant workers. I will first compare the molecular evolution of the Sb supergene with the non-driving homologous haplotype over multiple bearer and outgroup species. Then I will compare patterns of expression of Sb supergene genes in antennae and brains between workers. Lastly, I will functionally validate candidate genes by genetically altering their sequence in workers. I will assay the impact of the knock out on the Greenbeard effect by testing the queen-discrimination ability of transformed workers. Using this combination of techniques and analyses, the GreenAnt project will tackle the molecular basis and evolution of Greenbeard genes in metazoan organisms.



Net EU contribution
€ 203 149,44
Quartier unil-centre bâtiment unicentre
1015 Lausanne

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Schweiz/Suisse/Svizzera Région lémanique Vaud
Activity type
Higher or Secondary Education Establishments
Other funding
€ 0,00