Full-likelihood genomic inference resolves intergroup hybrid speciation in the only known parthenogenetic pleurodont...

Hybridization is increasingly recognized as an important evolutionary process that can reshape genomes and generate novel lineages. One striking outcome is the origin of obligately parthenogenetic populations, often through interspecific hybridization. Here, we use genome-wide data and coalescent models to reconstruct the evolutionary history of Liolaemus parthenos, the only known parthenogenetic pleurodont lizard. We sampled the darwinii complex (L. darwinii, L. grosseorum, L. laurenti, and L. parthenos) and L. josei from the donosobarrosi group, selected as a candidate paternal lineage based on phylogenetic and biogeographic evidence. Mitochondrial data place L. parthenos within northern L. darwinii, consistent with a maternal origin, whereas nuclear genomic summaries position it between L. darwinii and L. josei. Bayesian model comparison supports a hybrid speciation model involving northern L. darwinii and L. josei, rejecting alternative parental combinations and models without introgression. Triangle plots further support a stabilized hybrid lineage. Climatic niche analyses reveal strong divergence from northern L. darwinii but substantial overlap with L. josei, partially supporting geographical parthenogenesis. More broadly, our study demonstrates the utility of model-based genomic approaches for resolving hybrid origins in non-model systems and expands the comparative framework for understanding the emergence and persistence of asexual vertebrate lineages.