How chromosomal inversions affect fitness - an empirical approach

Chromosomal inversions largely prevents recombination between the two homologous chromosomes in a pair and hence exchange of genes. This has some fundamental detrimental effects. First, crossing-over during meiosis inside the inversion will produce unbalanced (and lethal) gametes. Second, deleterious mutations are no longer easily purged and accumulates inside inversions.

Nevertheless, inversions are identified in increasing numbers of species in the wild, and from early studies of flies (where inversions are visible in microscope) we know they are involved in both local adaptation and speciation.

However, our knowledge about the mechanisms that drive the evolution of inversions and their role, not least in speciation, is very poor.

Marine snails (Littorina) show various degrees of reproductive isolation representing the speciation continuum from locally adapted ecotypes to fully separated sibling species.

Recently we found a number of large inversions that host genes and QTLs for local adaptation, some inversions are shared among species while others are unique.

The snails are archetypes for parallel evolution with similar phenotypes evolving repeatedly both within and among species in response to same types of selection pressures.

This is a perfect platform the empirical studies and in this project I will study selection on inversion arrangements and perform comparative analyses describing how inversions evolve over time with and without gene flow.