Chemodiversity is Closely Linked to Genetic and Environmental Diversity: Insights into the Endangered Populations of the Local Endemic Plant Sideritis Euboea Heldr. of Evia Island (Greece)

Sideritis euboea is a perennial medicinal, local endemic species to mountainous areas of Central and Southern Evia Island (Greece) with isolated populations threatened with extinction. In this context, a genetic and phytochemical survey has been performed to evaluate the present status of S. euboea inter- and intra-population diversity in three mountainous areas (Dirfis, Xerovouni, Ochi) of Evia, while its occurrence data have been used to define the species-specific climate requirements and to simulate the habitat suitability. Our analysis revealed differences between the populations concerning their polymorphism and genetic homogenity, resulting in a clear clustering of the main three populations based on PCA analysis. An admixture of individuals was identified between distant populations, indicating a possible gene flow between them. The phytochemical analysis revealed significant differences concerning their content in species-specific polyphenolic metabolites, especially isoscutellarein and hypolaetin derivatives; based on the PCA analysis of the cumulative polyphenolic groups’ pattern, two populations were the more distinctive, while different functional groups of metabolites could result to more clear clustering. The ecological profile analysis revealed that the more diverse S. euboea populations in terms of genetics and cumulative polyphenolics are found under comparatively wetter conditions with lower annual temperature and higher annual precipitation. The findings herein support the distinct climate in the habitats of the main populations of S. euboea from the three mountains, suggesting that all three populations should be considered as distinct units for conservation management with Mt. Ochi’s population firstly prioritized.