3.1. Current and future climate niche modeling
The models demonstrated outstanding predictive performance for both of the species under consideration. The ensemble predictions exhibited robustness in forecasting the potential climate niches of these species. Notably, the top-performing models for Z. spina-christi included GBM (AUC = 0.97, TSS = 0.89), MaxEnt (AUC = 0.97, TSS = 0.85), Ensemble (AUC = 0.97, TSS = 0.86), and GLM (AUC = 0.93, TSS = 0.77). Conversely, for Z. nummularia , the most effective algorithms were MaxEnt (AUC = 0.99, TSS = 0.96), GBM (AUC = 0.99, TSS = 0.98), Ensemble (AUC = 0.99, TSS = 0.97), and GLM (AUC = 0.98, TSS = 0.95).
The key factors influencing the climate niche of Z. spina-christi , as determined by the contribution of three algorithms, were the maximum temperature of warmest month (38.94%), precipitation of coldest quarter (14.37%), and precipitation seasonality (13.73%). In the case of Z. nummularia , precipitation of coldest quarter, maximum temperature of warmest month, and isothermality played the most significant roles in predicting its distribution, accounting for 32.65%, 18.70%, and 13.92% of the contribution, respectively.
The habitat potential distribution map, created using the ensemble framework, indicated that under current climatic conditions, approximately 161 × 103 km² (9.78%) of the study area (covering 1,648,195 km²) – encompassing seven southern provinces, namely Khuzestan, Kohgiluyeh-Boyer Ahmad, Fars, Bushehr, Hormozgan, Kerman, and Sistan-Baluchistan along the Persian Gulf in the Saharo-Sindian phytogeographical region – is predicted to be suitable for Z. spina-christi . This suitability falls within the good (0.61-0.8) and excellent (0.81-1.0) threshold classes.
For Z. nummularia , the suitable habitat area was estimated to be about 71,684 km² (4.34%) of the country, with 78,599 km² (4.76%) falling within the sound and excellent suitability classes. Notably,Z. nummularia ’s distribution covers a smaller area compared toZ. spina-christi , spanning approximately 23,330 km² (1.41%) of the country’s area under current climatic conditions, primarily concentrated in the southwestern and western regions of Iran. The acceptable suitability threshold for Z. nummularia was defined with an estimated 16,777 km² (1.01%) and 14,650 km² (0.88%) of the country falling into the good and excellent suitability classes, respectively (Fig. 2).Top of Form