Comparative assessment of habitat suitability and niche overlap of three medicinal and melliferous Satureja L. species (Lamiaceae) from the eastern Adriatic region: Exploring potential for cultivation

Abstract

In Croatia, there are three Satureja species groups (tSsg) within the Satureja L. genus that are most widely used as medicinal and melliferous plants: the Satureja montana complex, S. subspicata complex and S. cuneifolia. Due to the high melliferous and medicinal potential of these taxa, our objective was to comparatively assess the habitat suitability of the tSsg to estimate their cultivation potential in the eastern Adriatic region. In addition, we assessed their overlaps in geographic and environmental space and investigated the occurrence of the putative hybrid taxon S. × karstiana in the areas of overlap between the two parental taxa (S. montana and S. subspicata). Finally, the differences in the environmental preferences of these three related species groups were investigated. The species distribution models were built using the maximum entropy method (MaxEnt) based on the occurrences of the tSsg, obtained from our field research in 2018–2021 and partly from the Flora Croatica Database. Six environmental variables (three bioclimatic and three topographic) were selected as predictors. The potential habitat suitability of the tSsg under current conditions showed high predictive model performance, with AUC values ranging from 0.890 to 0.910 ± 0.025. The environmental predictors with the highest mean percent contributions to the models were annual temperature range (Bio 7) for S. montana (74.3%) and S. subspicata (65.9%) and downwards surface solar radiation (Srad) for S. cuneifolia (40%). Majority (>90%) of the known S. × karstiana hybrid occurrences were found within the areas of habitat suitability overlap between the two parental taxa, confirming the model accuracy and efficiency in the discovery of putative hybrids. Finally, the niche overlap in environmental space between the investigated taxa pairs was the highest between S. montana and S. subspicata, enabling their hybridization, and lowest between S. cuneifolia and S. subspicata. Due to the widest potential distribution and broadest environmental niche, our results suggest that S. montana has the highest potential for cultivation for medicinal and melliferous purposes in the eastern Adriatic, particularly in light of ongoing climate change.