Geographic distribution pattern and ecological niche differentiation of endangered Opisthopappus in Taihang Mountains

Environmental changes could dramatically affect biodiversity and the distribution of species. Predicting and understanding the dynamics of vegetation distribution can provide valuable insights into ecosystems’ response to climatic and environmental changes. Opisthopappus (containing two species Opisthopappus taihangensis and Opisthopappus longilobus) is an endangered and endemic genus in the Taihang Mountains of China, which is regarded as a center of distribution and diversity for many plant genera. However, little is known about climatic and environmental changes impact on the distribution of Opisthopappus. Thus, based on maximum entropy model (MaxEnt), we predicted the potential distribution under past, current and future climate conditions, explored the niche difference between the two species and determined the critical environmental factors. Our findings revealed that the distribution areas of O. taihangensis increased from the last interglacial to the last glacial maximum (LGM) periods, while that of O. longilobus decreased gradually. Compared to LGM, O. taihangensis and O. longilobus decreased their distribution ranges in the mid-Holocene period, which are generally similar to the current distribution areas of two species. In the future periods, the predicted distribution areas increased for both species and presented a trend toward the center areas of the Taihang Mountains. Meanwhile, precipitation of wettest month and isothermality were the most important factors influencing the distribution of Opisthopappus. Significant niche differentiation between O. taihangensis and O. longilobus occurred gradually with time. These results provide useful information for understanding evolution and conservation of O. taihangensis and O. longilobus in Taihang Mountains.