Caenorhabditis briggsae strain:AF16 Genome sequencing

To systematically isolate the HI loci between the nematode species pair, we first generated 96 chromosomally integrated, independent GFP insertions in the C. briggsae genome. We next mapped the GFP insertion site into defined locations using a method we had developed earlier. The dominant and visible markers facilitated the directional crossing of its linked genomic sequences into C. sp.9. We then backcrossed each individual marker into C. sp.9 for at least 15 generations and produced 111 independent introgression lines, which together represent most of the C. briggsae genome. We finally dissected the HI patterns by scoring embryonic lethality, larval arrest, sex ratio, fertility, male sterility and inviability in a subset of the introgression lines, and identified pervasive HIs between the two species. The study produced a genome-wide landscape of HI between nematode species for the first time.