Abstract: [Objective] In this study, we analyzed the environmental divergence between the endemic homoploid hybrid tree species Picea purpurea and its progenitors P. wilsonii and P. likiangensis and predicted the change of their potential distribution under climate change for two future periods:2050s and 2080s.[Method] On the basis of collected geographical distributional information, the geographical information system software(ArcGIS)was used to obtain the environmental variables which was related to the distribution of P. purpurea and its parental species. Then the ecological divergence was quantified via Kruskal-Wallis multiple-range test, discriminant function analysis (DFA), and principle components analysis (PCA) etc. The distribution patterns of three Picea species under different climate change scenarios (i.e. the lowest, moderate, and the highest greenhouse gas emission scenario; RCP2.6, RCP4.5 and RCP8.5) were estimated using maximum entropy analysis(MaxEnt)and three general circulation models (BCC-CSM1-1,CCCma_CanESM2 和CSIRO-Mk3.6.0) for the 2050s and the 2080s.[Result] The results from Kruskal-Wallis tests, DFA and PCA indicated that the water and heat availability for P. purpurea were all significantly different from its parental species. That is, despite of the precipitation of coldest and warmest quarter of P. purpurea was intermediate between its progenitors, its soil moisture was significantly higher than them; the min temperature of coldest month of P. purpurea was significantly lower than that of its parental species, and the ground-frost frequency of P. purpurea was inversely higher than that of its progenitors. Furthermore,results from simulation-based estimates revealed that the potential distribution area for P. purpurea would decrease (about 5%) in the 2080s only under RCP2.6, while in the 2050s of this scenario and under other two scenarios, its distributional area in the two time periods were higher than the current. After integrated all three scenarios and two time periods, the potential distribution area of P. purpurea would increase by an average of 17% in the future, and exhibited an expansion tendency from the edge of southeast of Tibetan Plateau to its northeast inner. In contrast, the potential distribution of P. wilsonii would be severely threated by the climate change, its distributional area would decrease by average of more than 21% in the future (after integrated all three scenarios and two time periods). The potential distributional area of P. likiangensis would decrease by an average of 5% for all scenarios and periods in the future than current (after integrated all three scenarios and two time periods), excepted for the 2080s under both RCP4.5 and 8.5 (slightly higher less than 2%).[Conclusion] We demonstrated the environmental divergence between the homoploid hybrid species P. purpurea and its parental species in this study:the higher soil moisture and the low temperature in the winter were the key factors that driving the ecological divergence in P. purpurea from its progenitors. The potential distribution area of P. purpurea would significantly increase in the 2050s and 2080s. This suggests that P. purpurea plays an important role in ecological security and protection in the future.

Key words: Picea purpurea, ecological divergence, climate change, geographical information system, species distribution models(SDMs)