Collaborative Research: ORCC: Trophic phenotypes as eco-evolutionary mediators of resilience to climate change

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As lakes and other habitats continue to change in response to a warming climate, it is important to identify which ecosystems and organisms will be most vulnerable or able to persist. The thirteen populations of Arctic charr in Maine, USA, are the most southern remaining populations of this cold-adapted species and are expected to face challenges from climate warming and species invasions. We hypothesize that the ability of such populations to shift their diets and feeding traits may be especially important to their future persistence. This study investigates four of these charr-bearing lakes to determine how their habitat and food webs differ, and how this relates to specific Arctic charr behaviors and feeding traits. Electronic tags that emit sound will be used to track the movements of individual charr at fine scales. Twenty years of genetic samples will help determine how charr traits might change from adaptation or other processes. Quantitative models will be used to predict how differences in diet and habitat affect growth and population productivity, and subsequently the resilience of Arctic charr populations to continued warming and changes in habitats. Studying Arctic charr in Maine will help the conservation and management of not only this species, but also assess theory relevant to other species at the southern edge of their ranges. The project scientists will work closely with conservation groups and management agencies to ensure knowledge gained is quickly and effectively communicated for benefit. Many trailing-edge populations of fishes and other taxa inhabit small refuge habitats that are isolated and thus presumed vulnerable to interacting abiotic and biotic factors that could compress their niche to the point of collapse. This project tests an organismal-eco-evolutionary framework for assessing the role of trophic trait diversity and change in resilience to climate change, linking the genetic and plastic components of trophic trait variation to population demography, habitat and community contexts, and ultimately eco-evolutionary potential for persistence. Landlocked Arctic charr in Maine, USA, are the most southern populations of this species in North America. Moreover, there is evidence among Maine Arctic charr populations that populations are trophically divergent and that trophic trait variation can change in response to changes in resources. This project will integrate information on Arctic charr genotypes, phenotypes (morphology), diet, and movements (acoustic telemetry) with limnology and food web structure information to generate potential mechanistic links among variation in genotype, phenotype, and communities. Genetically inferred pedigrees and whole genome sequencing approaches will be integrated with phenotypic data and long-term (20 year) mark-recapture analysis of charr to estimate genetic and genomic parameters affecting trait lability and population dynamics in contemporary time. Individual-based models will simulate the bioenergetics and persistence of charr across trophic traits under a variety of temperatures, fish community compositions, and lake ecosystem types. Collectively, this research will improve the ability to predict the fate of trailing-edge populations through the lens of complex ecological feedbacks among climate change, intra- and interspecific interactions, and phenotypes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.