The "adaptive landscape" is very important for evolutionary biology, but rarely measured, Martin said. He's been fascinated with the concept since high school.
An adaptive landscape takes variable traits in an animal or plant, such as jaw size and shape, spreads them over a surface, and reveals peaks of success (what evolutionary scientists call fitness) where those traits become most effective, or adaptive.
It is a common and powerful idea that influences thinking about evolution. But while the concept is straightforward, it is much harder to map out such a landscape in the wild.
For example, about 50 species of pupfish are found across the Americas. The tiny fish, about an inch or so long, mostly eat algae on rocks and other detritus. Martin has been studying species found only in a few lakes on the island of San Salvador in the Bahamas, where some of the fish have evolved different-shaped jaws that allow them to feed on hard-shelled prey like snails or, in one case, to snatch scales off other fish.
In a paper published in 2011, Martin showed that these San Salvadoran fish are evolving at an explosively faster rate than other pupfish.