Abstracts (first author)
Genomic changes under rapid evolution: selection for parasitoid resistance
Most studies of selection in experimental populations so far have focused on long term selection pressures of relatively small effect. In this study we use the parasitoid Asobara tabida as a strong, fast and ecologically relevant selection pressure on four replicate selection lines derived from an outbred, natural population of Drosophila melanogaster. Parasitoids are insects whose larvae feed on a host in order to complete development and in this process kill the host. In the Drosophila genus the ability to successfully induce an immune response to encapsulate and melanize a parasitoid egg, is present in the melanogaster subgroup, where D. melanogaster shows a high level of variation in immune defense.
By combining artificial selection and whole genome HT-sequencing we identified several genomic regions carrying a signature of selection. In these selected regions we selected candidate genes associated with one or more significant SNPs, which potentially confer increased resistance against parasitoid attack. We propose that a 600kb region on chromosome 2R is a region of major effect on parasitoid defense, as it is highly enriched in highly significant SNPs.
The power of our approach is that we use replicated artificial selection experiments and a natural selective agent on an outbred D. melanogaster strain. This enables us to show very narrow genomic ranges that have been affected by selection, even under such a fast and strong selective regime. In addition to providing a much more detailed insight in how rapid evolution impacts the genome, it has also given us specific hypothesis on the genes and genomic regions that confer higher defenses against parasitoids.