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Mimulus guttatus

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The monkeyflower Mimulus guttatus grows along stream banks and seeps in northern California, but it is rarely found in the drier gulches and rocky outcrops where its close relative Mimulus nudatus grows, often just an arm’s length away. In a new study, Duke biology Ph.D. Katherine Toll and professor John Willis found that M. nudatus seedlings that sprout in M. guttatus’ flooded habitat probably die underwater. What’s more, the rare immigrants that spread into the other species’ turf are often cross-pollinated, producing shriveled hybrid seeds that rarely germinate. The results help explain how fledgling species coexist without fusing back together.