Figure 4.

Location of the Raalte sampling location (white circle) relative to modern natural distributions of the oak sections Quercus sensu stricto and Cerris. Line 1 represents the northern limit of oaks in the section Quercus and of all oaks in the Western Palaearctic. Only section Quercus oaks are native between lines 1 and 2. Line 2 represents the northern limit of the natural distribution of section Cerris oaks. Oaks in sections Quercus and Cerris are naturally found together between lines 2 and 3. Line 3 represents the southern limit of oaks in the section Quercus. Only section Cerris oaks are found between lines 3 and 4. Line 4 represents the southern limit of section Cerris oaks. Distributions are based on regional floras as explained in Stone et al. (2007).