We focus on the recently diverged Formica rufa group wood ants, many of which occur in Southern Finland with overlapping distributions.
We have studied hybrid and parental wood ant populations over 10 to 15 years and discovered that natural selection acts differently on males and female hybrids. Some years hybrid females are favored but males are selected against. This differential natural selection is likely caused by the fact that females are diploid and males are haploid. In haploid males all the recessive problems of hybridization are exposed to selection. This makes ants a good model system for speciation genomics; genomic regions that prevent gene flow and lead to reproductive isolation are easy to identify.
Our current studies have identified several candidate barrier loci, that prevent gene flow between diverging species. Now we are confirming these candidates and testing if natural selection is actually acting on these loci in nature. At the same time we are utilizing large scale individual level transcriptome data set that will elucidate which gene expression patterns lead to hybrid breakdown in the males and testing the role of gene interaction networks in speciation.
Our current studies are also focused on understanding how the environment and natural selection shape hybrid ant populations in Finnish forests. Our recent findings suggest temperature or another correlated variable could be an important determinant of hybrid fitness. Utilizing long-term genetic data from natural populations we ask is evolution repeatable in multiple hybrid populations? Is fluctuating temperature-dependent selection acting on natural wood ant populations?