Most species in the mustard family are restricted to higher elevations and latitudes where they also have restricted local spatial distributions. In this chapter, we describe a novel hypothesis for the development of low-elevation range limits in upland mustard species. The hypothesis suggests that defense regulation of glucosinolates could underlie the evolution of the spatially restricted distributions. A list of testable predictions is presented to evaluate the hypothesis. An interdisciplinary Ecological Genomics approach is needed to test the predictions; therefore, we also describe the field of Ecological Genomics. Although there is already support for some of the predictions, which we discuss, most of the predictions remain untested. Therefore, we also describe several tests that help evaluate each of the predictions.
Part of the book: Abiotic and Biotic Stress in Plants