Figure 2.

The phylogenetic history of two closely related ecotypes under the stable ecotype model. After each periodic selection event, indicated by an asterisk, only one variant from an ecotype survives. After periodic selection, the descendants of the surviving variant diverge (indicated by dashed lines), but with the next periodic selection event, again only one variant survives. Note that a sequence-based phylogeny of two ecotypes will indicate very limited sequence diversity within an ecotype, with much greater sequence divergence between members of different ecotypes. This model yields a one-to-one correspondence between ecotypes and sequence clusters. (Used with permission from the Thermal Biology Institute.)