Our research focuses on understanding how variation is generated and maintained in natural populations. In particular, we are interested in understanding both the proximate (i.e., molecular, genetic, developmental and neurobiological mechanisms) and ultimate (i.e., timing, strength and agent of selection) causes of evolutionary change. Thus, much of our research focuses on identifying and characterizing the molecular changes responsible for traits that affect fitness of organisms in the wild. To this end, we use an interdisciplinary approach combining molecular techniques (ranging from next-gen sequencing and transcriptomics to cell-based pharmacological assays and in vivo viral vectors), population-genetic tests, classical genetic crosses, lab-based behavioral assays and field-based experiments. We focus primarily on natural populations of rodents in which ecological and genomic information can be combined to address fundamental questions about the evolution of morphological, behavioral and reproductive diversity.