Nuclear and Chloroplast Markers Provide New Insights Into the Syngameon Dynamics of Genus (Lamiaceae) in the Canary Islands.

Species syngameons are groups of more than two hybridizing species that form complex hybrid networks. Syngameons facilitate sharing the gene pool among species while maintaining morphological differentiation. In oceanic islands, hybridization is common, and syngameons are expected to be common and play an important role in increasing standing variation in the face of the founder effect associated with the colonization process. The mechanisms of how these syngameons are formed and maintained, the impact islands' geological history has on syngameons, and their evolutionary consequences remain unknown. Using the genus (Lamiaceae) in the Canary Islands as an example, we aim to describe the structure of the syngameons and evaluate if it varies across island age, taxa, and genomic region. For this, we used 14 Exon primed intron spanning (EPIC) nuclear markers and 12 chloroplast (cpDNA) markers to conduct phylogenetic and genetic diversity analyses. The results show that species in younger islands have higher genetic diversity and share haplotypes with more taxa than species in older islands. Moreover, widespread taxa have higher intraspecific connectivity than taxa with narrower distributions. These findings suggest that species syngameons are larger and more complex in younger islands and that widespread taxa are key players in maintaining them. This pattern and phylogenetic signal were not consistent across loci and genomic compartments, indicating that different genomic regions may show different perspectives on syngameons dynamics. This study provides evidence that island ontogeny, degree of evolutionary divergence, and species distribution range shape the formation, expansion, and maintenance of syngameons.