My research integrates evolutionary biology, genetics, and field ecology to understand how natural processes and anthropogenic stressors shape the genetic constitution of populations and species, and how this in turn influences adaptation and sustainability. I address three general questions in my research program: (1) What factors promote or constrain dispersal and gene flow? (2) How do dispersal pathways and ancestral histories shape contemporary adaptation? (3) What is the relationship between genetic and phenotypic variation? These three questions tie into a unified framework for understanding interrelationships among natural selection, gene flow, and phenotypic plasticity, which are predicted to have interactive effects on adaptive phenotypic variation (Crispo 2008, J. Evol. Biol. 21:1460-1469; Figure 1). Populations of freshwater fishes are under threat worldwide due to a number of environmental stressors. Lessons from my work apply to processes in other natural systems as well and can inform conservation decisions.

Given the global decline in species numbers, integrative research in the field of biodiversity science is critical. Genetic variation is the building block of higher-level diversity, and thus understanding the factors that shape the genetic constitution of populations and species is of fundamental importance. These could be geographical features that shape dispersal patterns, or patterns of natural selection that influence gene introgression. The evolution of phenotypic plasticity as an adaptive strategy might be increasingly important given the rapid rate of environmental change. Due to both natural and human influences, standing genetic variation might be too low in some populations to permit adaptation to changing conditions. Thus the study of gene regulation will become increasingly relevant in conservation science. Through the integration of these approaches in the above mentioned systems, my research will help elucidate the factors affecting species distributions and the maintenance of biodiversity.

Figure 1. Diagram depicting potential relationships among selection, adaptation, plasticity, and gene flow. Divergent selection can lead to local adaptation or to the evolution of plasticity. Gene flow can have negative consequences for adaptive divergence, through genetic swamping; or positive effects, through the spread of beneficial mutations. Gene flow might also promote the evolution of plasticity, if the plastic response increases the average fitness across environments. Plasticity and adaptation might interact, such that the plastic response permits colonization of new environments, which subsequently leads to local adaptation; or, plasticity can render local adaptation redundant, and vice versa. (Figure from Crispo 2008, J. Evol. Biol. 21:1460-1469.)