Review Article

Ecological Speciation and the Intertidal Snail Littorina saxatilis

Figure 2

The two ecotypes H and M on three Yorkshire shores group by ecotype (a) when the loci under selection are included in a neighbour-joining tree using Nei’s genetic distance, but by shore when those 15 (out of 290) loci are excluded from the analysis. One shore (Robin Hood’s Bay) has only the M ecotype, and here there are two samples, separated by 75 m on the shore. The other three shores have both ecotypes separated by 5 m (Thornwick Bay), 15 m (Filey), and 300 m (Old Peak). Bootstrap values are shown on the tree. The shores are along a 45 km stretch of coast (redrawn from Wilding et al. [25]).