Evolution’s Wedges

Finding the genes that drive one species into two

Look to Texas to see evolution’s true colors. There, speckling the state’s green fields, you’ll find the annual phlox, a flower also known as “Texas pride.” Its petals, a light purple elsewhere, are bright scarlet in the southeast near Austin. This color change isn’t a whim: It’s the annual phlox’s response to the presence of a close cousin, the pointed phlox.