Adaptive transgenerational signaling; maternal and paternal effects on early life history in salmon

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We know that local environmental conditions, like pollution and temperature changes, cause corresponding changes in early life stages of organisms that are reflected at the DNA level. These environmental changes can be rapid, and require the organism to adapt and evolve equally rapidly or face extinction. This strong selection and rapid evolution does not fit into a classical genetic selection model, so what is allowing these organisms to quickly alter the way their early life stages play out in response to changes in local environmental conditions? My previous NSERC research focused on characterizing early life history variation in fish, with a particular focus on salmon. The results of that work have led me to conclude thatcontrary to widely-held theoriesthe rapid, responsive evolution of early life stages is partly (or even mostly) due to maternal and paternal effects outside of classical genetic inheritance that affect offspring through transgenerational signaling (“TS”). While maternal effects have been found across taxa (paternal effects have not been as widely studied), we know very little about their adaptive potential or the subcellular mechanisms through which they work. So, this proposal addresses three important questions about TS as an evolutionary force for rapid adaptation: 1) “What are the genetic, epigenetic and environmental components of TS?”, 2) “What are the sub-cellular mechanisms of TS?”, and 3) “Does TS provide a measureable benefit for offspring fitness?” By answering those questions among populations of Chinook salmon and rainbow trout, I will determine if TS is a major driver of local adaptation in salmon. Specifically, I will manipulate maternal and paternal environments independently in nested breeding experiments, allowing direct maternal and paternal effect estimation. I will explore the specific sub-cellular (epigenetic) factors contributing to TS, and determine how variation in those signals affect offspring fitness. My proposed research program will have important implications for both basic and applied sciences. Although there are many examples of rapid evolution, my research will contribute to our understanding of how this evolution takes place. Specifically, my NSERC research will contribute to evolutionary and ecological theory by redefining TS as an exciting and novel paradigm for rapid evolution of local adaptation to environmental variation and stress. The applied outcomes will not be limited to salmon, or even fishes, but would apply to all vertebrates exhibiting local adaptation. Managers and conservation biologists will change how they work to preserve local populations: the unit of conservation would switch from “populations” to “TS profiles.” Hatchery managers (both government and aquaculture) will focus on how the parents are treated prior to breeding to improve reintroduction, supplementation and commercial culture success.