Molecular mechanisms of sympatric speciation in a socially parasitic ant

Whether new species can form in sympatry is an unsolved and fundamental problem in evolutionary biology.

Convincing cases from nature are few, hampering our understanding of how and when sympatric speciation occurs. “Inquiline” social parasites in ants have long been recognized as promising systems for sympatric speciation.

However, there are currently no genomic studies attempting to understand the molecular basis of traits causing divergent selection between speciating lineages, or identifying molecular barriers to gene flow, in such systems.

I propose to do both in Myrmica rubra, a species in which socially parasitic ant queens (“microgynes”) are currently speciating in sympatry from normal, non-parasitic, ant queens (“macrogynes”).

I have identified a 7 Mb supergene polymorphism in M. rubra and its sister species M. ruginodis, which also has microgyne and macrogyne queens but where microgynes are neither parasitic nor speciating.

Based on preliminary results showing haplotype differences between macrogynes (AB) and microgynes (BB), I hypothesize that this supergene is involved with queen polymorphism in both species and acts as a barrier locus between M. rubra queen morphs.

I will test these hypotheses in a three-year research project based at the universities of Oulu (Finland) and Uppsala (Sweden), using whole-genome sequencing data.

The results will contribute to our understanding of the molecular basis of adaptation and sympatric speciation in a haplodiploid system.