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

## TL;DR

This study shows that hybridizing species networks (syngameons) in the Canary Islands are more complex on younger islands and involve widespread species, with patterns varying across genomic regions.

## Contribution

The study reveals how island age, species distribution, and genomic regions influence syngameon dynamics in Micromeria.

## Key findings

- Species in younger islands have higher genetic diversity and share haplotypes with more taxa.
- Widespread taxa show higher intraspecific connectivity and help maintain syngameons.
- Syngameon patterns vary across genomic regions, indicating different genomic perspectives on hybridization dynamics.

## Abstract

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 Micromeria (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.

This study explores species syngameons, hybridizing networks that facilitate gene pool sharing while maintaining species differentiation, using Micromeria in the Canary Islands as a model. The findings reveal that syngameons are larger and more complex on younger islands, with widespread taxa playing a critical role in maintaining these networks. The results also highlight variability in syngameon patterns across genomic regions, suggesting that island age, evolutionary divergence, and species distribution influence syngameon formation and dynamics.