The Sierra Nevada yellow-legged frog evolved in the fishless waters of Yosemite: '... advent of fish in a lake sooner or later nearly or quite eliminates the frogs. It seems probable that the fish prey upon the tadpoles, so that few or none of the latter are able to reach the stage at which they transform. The frogs which live along the streams probably spawn in small temporary pools in the meadows which the trout cannot reach.' - Animal Life in the Yosemite by J. Grinnell and T.I. Storer, 1924.