SFB-TRR 212

Proximate and ultimate mechanisms of social niche construction during colony founding in the ant Pogonomyrmex californicus

Social organisms interact constantly with other individuals and try to shape their social niche according to their fitness interest using different strategies like cooperation, selfishness, altruism or spiteful behaviour. Newly mated ant queens of Pogonomyrmex californicus can found their colonies either alone or in groups. Surprisingly, these founding associations stay together and unrelated queens and workers cooperate for the rest of the colony life, which is a major transition from kin based groups to non-kin based groups. We study the genetic and epigenetic architecture and evolution of social niche construction in the context of colony founding and the evolution of non-kin based social groups.

We plan to develop a generalised evolutionary framework that takes into account the relationships between genotype, phenotype, social niche and fitness to understand the maintenance and evolution of social niche polymorphism and the underlying social niche construction mechanism.

ATACseq and ChIPseq experiments will be complemented with pharmacological inhibitions of histone acetyle transferase (HAT) and histone deacetylases (HDACs) in founding queens to manipulate their behaviour. We will also use dsRNAi knockdowns of candidate genes in founding queens to confirm niche construction/aggression modulating genes. In addition to aggressive behaviour, we will also focus on division of labour (digging, brood care, egg laying) as those are important behaviours that modify a queen`s social niche.

We will pursure three main aims:

1.  Confirm that our candidate genes and epigenetic differences are causally linked to the observed gene expression and behavioural differences underlying social niche construction.
2. Determine whether genetic and epigenetic differences between the two social types are maintained in a sympatric population.
3. Comparing changes in the gene expression patterns and histone marks of queens from founding colonies of different group sises (including spiteful behaviour).

These experiments will determine the upper bound of possible social niches in terms of queen number for P. californicus foundress associations and will be the first study of molecular mechanisms underlying optimal group size evolution.