Abstracts (first author)
Copy-number changes in experimental evolution: rates, fitness effects and adaptive significance
Gene copy-number differences due to gene duplications and deletions are rampant in natural populations and play a crucial role in the evolution of genome complexity. The rate at which new gene copies appear in populations greatly influences their evolutionary dynamics and standing gene copy-number variation in populations. The duplication rate may therefore have profound effects on the role of adaptation in the evolution of duplicated genes with important consequences for the evolutionary potential of species.
In this talk, I will discuss three long-term experimental evolution experiments in Caenorhabditis elegans that we have utilized to investigate fundamental properties of the gene duplication process. First, we conducted oligonucleotide array comparative genome hybridization (oaCGH) on C. elegans mutation accumulation (MA) lines subjected repeatedly to single-worm bottlenecks each generation to provide the first direct estimate of the spontaneous genome-wide rate of duplication in a multicellular eukaryote. The gene duplication rate in C. elegans is quite high and exceeds the spontaneous rate of point mutation per nucleotide site in this species by two orders of magnitude. Second, I discuss new oaCGH results of low-fitness experimental lines subjected to adaptive recovery via population expansion to investigate whether copy-number variants (CNVs) constitute a common mechanism of adaptive genetic change during compensatory evolution. Lastly, long-term spontaneous MA lines maintained at three varying effective population sizes for >400 generations were used to investigate whether CNVs accumulate differentially under varying intensities of natural selection and provide some insights into their average fitness effects.