Proximate and ultimate mechanisms of social niche construction during colony founding in the ant Pogonomyrmex californicus (SFB-TRR 212)

Basic data for this project

Description

Ants have an impressive ability and flexibility to organise and construct their social environment leading to a large variety of realised social structures or social niches (Hölldobler & Wilson 1977, Saltz et al. 2016). One of the most important evolutionary components of colony structure is the number of reproductive individuals (queens) and their relatedness in multi queen societies (Hölldobler & Wilson 1977, Keller 1993, pp 439 ff). Small changes in behavioural interactions like accepting newly mated queens back into the colony or collaborating with related or unrelated queens during colony founding can change the social structure and have dramatic fitness effects at the individual, colony and population level (Bourke & Heinze 1994, Goodisman & Ross 1998, Libbrecht & Kronauer 2014, Meunier et al. 2011). Many previous experimental and theoretical studies have focused on the ecological factors, behavioural mechanisms and fitness consequences of individual candidate genes. But very little is known about the genetic and epigenetic architecture and molecular evolution of these mechanisms in relationship to social niche construction with the exception of the social supergenes in Solenopsis invicta and Formica selysia (Linksvayer et al. 2013). Saltz et al. (2016) define a social niche “as the set of social environments in which the focal individual has nonzero inclusive fitness”. Social niche construction is therefore any behaviour that changes the adaptive social environment of an individual analogous to niche construction where traits of an organism adaptively changes the environment that it experiences (Odling-Smee et al. 1996, Saltz 2011, Saltz & Nuzhdin 2014). Our project will take into account how the genetic and epigenetic architecture and social context shapes an individual queen`s social niche. We have (first funding period) and will simultaneously study the genomic composition, expression and epigenetic changes of interacting founding queens in different social settings from three populations (H- (haplometrotic), P- (pleometrotic), and M- (mixed population) population) and determine the fitness outcome of these different social niches at an individual and group level. In the first funding period, we identified candidate genes and a supergene, epigenetic mechanisms and gene expression differences between interacting founding queens that directly and indirectly affect a queen`s social behaviour and fitness (see also Vojvodic et al. 2015). These findings and the planned experiments in the second period will provide us with a systems-level insight into the molecular basis of social regulation. For confirmation, we will use both gene- or systems level experimental approaches (e.g. dsRNAi or pharmacological interferences) to manipulate expression and quantify effects at the individual- and group level (Linksvayer 2015). Once we understand the genotype-phenotype mapping (Alberch 1991, Pigliucci 2010), we can better understand and model evolutionary processes, e.g. how allelic variation and epigenetic modifications and the interaction of direct and indirect genetic effects influence phenotypic traits like expression or social behaviour and their evolution (sensu systems genetics; Ayroles et al. 2009, Linksvayer 2015)