The distribution of a species is thought to be limited by physiological tolerances to the environment, interactions with other organisms, or genetic constraints on adaptation. In this project the importance of these factors on adaptation will be studied using populations sampled across the range of a naturally endemic flowering plant (Mimulus bicolor). Plant populations will be grown in growth chambers with varying precipitation and temperature regimes to determine whether plant fitness is limited by physiological tolerances to environments expected at the range edge. The role of genetic constraints on adaptation will be inferred by studying patterns of population genetic diversity to determine whether populations at range edges are effectively small, inherently isolated, or experience maladaptive gene flow from populations at the center of the species range.
Understanding the mechanisms that limit the distribution of species will increase our ability to predict how the distribution of species will shift in the face of climate change. In addition to answering this broad question, the research will train a graduate student and undergraduate students to conduct experiments in controlled environments and to use genetic markers to determine population structure and patterns of gene flow. Each of these approaches will provide critical information on species range limits and can be used for future management decisions regarding species range shifts. Students will present their work at research meetings, which will disseminate their findings to other scientists and researchers.
