DISSERTATION RESEARCH: Landscape genetics and connectivity in a polymorphic salamander, Plethodon cinereus

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This project will investigate the ecological and evolutionary factors that maintain color polymorphism in different populations of the Eastern Red-backed Salamander, a species that has a 'striped' red and black morph and an 'unstriped' solid black morph. Many species in nature have multiple color morphs that occur together within a single population. However, the frequencies at which particular morphs occur can vary widely among different populations. A fundamental unanswered question in evolutionary ecology is whether natural selection or dispersal is primarily driving these differences. This study will collect and analyze genomic data from 32 Eastern Red-backed Salamander populations that range from having only a single color morph present to having both morphs present at various frequencies. Different morphs of this species also differ in other aspects of their biology, such as physiology and aggression, and a major goal is to assess the relative importance of local adaptation versus dispersal among populations in maintaining morph frequencies. Results will further our basic understanding of the relationship between color variation and the evolution of diversity. In addition, the project will provide research opportunities for undergraduate students, who will be trained in cutting-edge genetic techniques. Outreach includes public seminars at two local nature preserves and educational displays at the local library for school children.This project will use genomic data to determine whether geographic distance, environmental variables, morph frequency, or a combination of these factors best explain patterns of genetic variation in the Eastern Red-backed Salamander, Plethodon cinereus. Genetic data will be collected using double digest restriction associated DNA (ddRAD). These data will be used to quantify levels of gene flow in P. cinereus from 480 individuals from 32 populations across northern Ohio that vary in morph frequency, from monomorphic to various degrees of polymorphic. A variety of statistical analyses, such as STRUCTURE, BAYESCAN, and redundancy analysis, will be used to determine if genetic variation in P. cinereus is more closely linked with phenotype frequency or geographic distance. Overall, this study will provide critical information on the relative contributions of morph frequency and geographic distance for explaining patterns of genetic variation in P. cinereus, and will improve our understanding of the factors involved in the evolution and maintenance of color polymorphisms.