a significant trendp < 0.001
Using a generalized additive mixed model (GAMM 51 ), which accounts for the temporal structure within the data by specifying a correlation structure (corAR1), we test for change in the estimated size of the projected potential climatic niche space through time, from 145 ka to 30 ka ago and find a significant trend ( r 2 = 0.373, edf = 2, p < 0.001), in which as time progresses, there is a general pattern of contraction from the Eemian onwards (Fig. 5 ).