Figure 6 in Geographic isolation and human-assisted dispersal in land snails: a Mediterranean story of Helix borealis and its relatives (Gastropoda: Stylommatophora: Helicidae)

Figure 6. Schematic representation of three alternative dating scenarios for the Mediterranean clade. A, a tree calibrated by setting the mean uncorrelated relaxed clock rate to 0.02 substitutions per site per million years; B, C, alternative palaeogeographic calibrations based on the Messinian Salinity Crisis with the associated marine regression. Full black circles mark the nodes used as calibration; in B multiple nodes are marked since the dating scenario assumes all of these splits to occur during the shaded period at the latest. The shaded ranges depict (part of) the uncertainty associated with the calibration: B, the duration of the Messinian Salinity Crisis; C, the time during which the Mid-Aegean Trench formed. Outgroup was removed for plotting.