The monkey-flower is a colorful plant, with about 150 species worldwide. The largest species group is in western North America.
There are 2 nearly selfsame varieties of monkey-flower in California which live in the hills at different elevations. Low-elevation monkey-flowers are red, pollinated courtesy of hummingbirds. Up the slope are pink monkey-flowers, pollinated by bees.
A difference in pollinator is a common element of plant reproductive isolation. Honeybees on the hills don’t carry their pollen down, and hummingbirds prefer the lowlands.
In between the different elevations hybrid monkey-flowers do exist. They are not as robust and produce fewer seeds.