RADseq data of Bacillus crosses for reproductive mode inference
Many organisms reproduce through non-canonical modes such as parthenogenesis or hybridogenesis (clonal transmission of chromosomes from one parent), but whether these arise abruptly or stepwise from each other remains unclear. We address this in the stick-insect genus Bacillus, which harbors several hybrid lineages with diverse reproductive modes. From haplotype-resolved phylogenies of more than 500 wild-caught individuals, we infer a single, recent (ca. 8000 years) origin of all hybrids. The ancestral hybrid reproduced via hybridogenesis, which subsequently diversified into parthenogenesis and, twice independently, into triploid lineages. Laboratory crosses recapitulate this trajectory, where each step facilitated the next. These findings reveal how a single genomic perturbation can act as a catalyst for evolutionary innovation, turning the loss of sex into a driver of diversification rather than a dead end.