Trends and rates of microevolution in plants

Evidence for rapid evolutionary change in plants in response to changing environmental conditions is widespread in the literature. However, evolutionary change in plant populations has not been quantified using a rate metric that allows for comparisons between and within studies. One objective of this paper is to estimate rates of evolution using data from previously published studies to begin a foundation for comparison and to examine trends and rates of microevolution in plants. We use data gathered from studies of plant adaptations in response to heavy metals, herbicide, pathogens, changes in pH, global change, and novel environments. Rates of evolution are estimated in the form of two metrics, darwins and haldanes. A second objective is to demonstrate how estimated rates could be used to address specific microevolutionary questions. For example, we examine how evolutionary rate changes with time, life history correlates of evolutionary rates, and whether some types of traits evolve faster than others. We also approach the question of how rates can be used to predict patterns of evolution under novel selection pressures using two contemporary examples: introductions of non-native species to alien environments and global change.