Ecological niche differentiation and taxonomic distinction between Eremias strauchi strauchi and Eremias strauchi kopetdaghica (Squamata: Lacertidae) on the Iranian Plateau based on ecological niche modeling

Abstract Eremias strauchi strauchi and Eremias strauchi kopetdaghica are genetically and morphologically distinct and are distributed allopatrically in northeastern and northwestern Iran. E. s. strauchi is distinguishable by having green spots on lateral parts of the body, while E. s. kopetdaghica is characterized by white spots and irregular black dots on lateral parts of the body. Recent molecular studies have suggested that these are two distinct species, but other types of analyses leave their classification unclear. In this study, we evaluated their taxonomic status using additional data (including ecological niches) to confirm the hypothesis that they are two species. All known records of their occurrence were employed to predict and evaluate the suitable areas where they may be expected to be found in Iran. We then performed niche similarity tests (niche identity and background tests) and point-based analyses to compare their ecological niches and explain ecological differentiation. Niche models of E. s. strauchi and E. s. kopetdaghica had good results and powerful performance based on high area under the curve (AUC) values [E. s. strauchi = 0.992, standard deviation (SD) = ± 0.008; E. s. kopetdaghica = 0.978, SD = ± 0.032]. Ecological differentiation has been found across the entire range, indicating that ecological differentiation had an important role in species differentiation. Environmental conditions for the species diverged along environmental variables, as precipitation of coldest quarter for the “Strauch” subspecies and precipitation of warmest quarter for the “Kopet dagh” subspecies were most important in determining habitat suitability, respectively. These two factors are important in niche differentiation between the two species and influenced their genetic divergence. Finally, our results confirmed the niche differentiation between E. s. strauchi and E. s. kopetdaghica and added new insights into the taxonomic distinction between E. s. strauchi and E. s. kopetdaghica.