Figure 5 . Percentage of mixed ploidy versus absolute latitude; b) Pruned regression tree results based on percentage of mixed ploidy, the total deviance explained is variance remaining in the sum of the leaves as a proportion of the variance in the entire data set. Cut off values for the most important environmental variable are given at each split: Endemic species richness (End) maximum temperature of the warmest month (TMX), Maximum of the warmest month – minimum of the coldest month (TRG), average annual temperature (TYR), potential evapotranspiration (ET0), average temperature of the direst quarter (TDRY). The numbers at each leaf are the average percentage of mixed ploidy of the grid square in that group, c) The partial dependency plots showing the shape of the relationship between percentage of mixed ploidy and its best predictor variables: Endemic species richness (End) and average annual temperature (TYR).