Natural selection and the evolutionary dynamics of chromosomal inversions [MCB]
Genomes evolve through changes in DNA sequences and changes in chromosome number, structure, and gene content. Since the 1960s, population geneticists have overwhelmingly focused on protein and DNA sequence evolution, and it is only recently that they have begun to seriously focus on the evolution of genome structural changes. Chromosomal inversions are an important class of structural genetic variation that alters gene order within a chromosome, modifies recombination between chromosomes, and potentially facilitates adaptation and speciation. Several recent studies have shown that inversions contribute substantially to genome-wide evolutionary divergence between species. However, we currently know very little about the evolutionary processes driving inversion evolution, or how to empirically distinguish between different hypothetical scenarios for inversion evolution. I will present a series of population genetics models for the evolution of chromosomal inversions, each focusing on the relation between inversion size – which is readily quantifiable in genome sequence data – and inversion fixation probability. The models reveal that different scenarios of inversion evolution give rise to different predictions regarding the size distribution of fixed inversion differences between species. I discuss how the models may be used to test whether natural selection has contributed inversion evolution, and provide an example from Drosophila.
Dr Tim Connallon, Monash University