Although every species has a limited geographical distribution, there is tremendous variation in the size and the position of geographic ranges, even among closely related species. What are the main factors influencing the short- and long-term limits to specie’s distributions? This question has been a long-standing goal in, biogeography and evolutionary ecology and has recently returned with renewed interest due to an accelerated loss of biodiversity, climate change and the spread of invasive species. Understanding this fundamental question will help us predict whether species will be able to adapt to environmental changes, shift their ranges, spread elsewhere or go extinct. This presentation will address the short- and long- term factors that influence species range limits and the research on a coastal dune endemic plant from the Pacific coast of Baja California, California and Oregon.