TY - JOUR TI - Selfing is the safest sex for Caenorhabditis tropicalis AU - Noble, Luke M AU - Yuen, John AU - Stevens, Lewis AU - Moya, Nicolas AU - Persaud, Riaad AU - Moscatelli, Marc AU - Jackson, Jacqueline L AU - Zhang, Gaotian AU - Chitrakar, Rojin AU - Baugh, L Ryan AU - Braendle, Christian AU - Andersen, Erik C AU - Seidel, Hannah S AU - Rockman, Matthew V A2 - Castric, Vincent A2 - Weigel, Detlef A2 - Castric, Vincent VL - 10 PY - 2021 DA - 2021/01/11 SP - e62587 C1 - eLife 2021;10:e62587 DO - 10.7554/eLife.62587 UR - https://doi.org/10.7554/eLife.62587 AB - Mating systems have profound effects on genetic diversity and compatibility. The convergent evolution of self-fertilization in three Caenorhabditis species provides a powerful lens to examine causes and consequences of mating system transitions. Among the selfers, Caenorhabditis tropicalis is the least genetically diverse and most afflicted by outbreeding depression. We generated a chromosomal-scale genome for C. tropicalis and surveyed global diversity. Population structure is very strong, and islands of extreme divergence punctuate a genomic background that is highly homogeneous around the globe. Outbreeding depression in the laboratory is caused largely by multiple Medea-like elements, genetically consistent with maternal toxin/zygotic antidote systems. Loci with Medea activity harbor novel and duplicated genes, and their activity is modified by mito-nuclear background. Segregating Medea elements dramatically reduce fitness, and simulations show that selfing limits their spread. Frequent selfing in C. tropicalis may therefore be a strategy to avoid Medea-mediated outbreeding depression. KW - caenorhabditis tropicalis KW - selfing KW - mating systems KW - balancing selection KW - gene drive KW - population genetics JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -