Description
Interspecific hybridization often causes rapid purging of minor-parent ancestry, yet introgressed segments can persist in nature. Understanding how such ancestry is retained requires multigenerational experimental evolution, but this is impossible when complete reproductive isolation prevents hybrid propagation across generations. Here, we overcome complete hybrid male sterility between the nematodes Caenorhabditis briggsae and C. nigoni using an X-linked introgression line, enabling 100 generations of experimental evolution in diploid hybrids. Although minor-parent ancestry was rapidly purged genome-wide, several autosomal segments were recurrently retained. Analysis of a lineage evolved for 100 generations identified transmission ratio distortion (TRD) as a driver of minor-parent ancestry retention despite substantial fitness costs. Using fluorescently marked, homozygous-lethal autosomal introgression lines, we further show that TRD is widespread across minor-parent autosomes. Together, our results show that non-Mendelian transmission can counter genome-wide purging and promote the persistence of deleterious minor-parent ancestry, with implications for introgressed variation in nature.| Period | 21 Jul 2026 → 24 Jul 2026 |
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| Held at | 11th Asia-Pacific Worm Meeting, Australia |
| Degree of Recognition | International |