[
International Worm Meeting,
2021]
Life history traits underlie the fitness of organisms and are under strong natural selection. A new mutation that positively impacts a life history trait will likely increase in frequency and become fixed in a population (e.g. selective sweep). The identification of beneficial alleles that underlie selective sweeps provides insights into the process of natural selection that occurred during the evolution of a species. In the global population of Caenorhabditis elegans, we previously identified selective sweeps that have drastically reduced chromosomal-scale genetic diversity in the species. Here, we measured the lifetime fertility of 121 wild strains, including many recently isolated divergent strains from the Hawaiian islands, in standard laboratory conditions. We found that strains with larger swept genomic regions on multiple chromosomes have significantly higher fertility than strains that do not have evidence of the recent selective sweeps. We used genome-wide association (GWA) mapping to identify three quantitative trait loci (QTL) underlying fertility variation. The haplotype structure in each QTL region revealed correlations with recent selective sweeps in the C. elegans population. Moreover, North American and European strains showed significantly higher fertility than most strains from Hawaii, a hypothesized origin of the C. elegans species. These results suggest that beneficial alleles that cause increased fertility are associated with selective sweeps during the worldwide expansion of C. elegans. Additionally, we mapped previously collected fertility data (fertility of the first four days in the adult stage) of wild C. elegans strains and C. elegans recombinant inbred advanced intercross lines that were grown in various conditions and detected eight QTL across the genome using GWA and linkage mappings. Altogether, these 11 QTL show the genetic complexity of fertility across this species.