RUI: Evaluating selection via ocean acidification and evolutionary responses of two coastal fishes

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Ongoing increases in atmospheric carbon dioxide have changed the acidity of the ocean, which could affect growth and survival of marine organisms. For fishes, the projected decreases in ocean pH could cause severe increases in mortality during the larval and juvenile stages. In turn, these effects may lead to major reductions in the numbers and size of adult fish, loss of fishery yields, and a loss of income for people whose livelihoods depend on the sea. However, if species can genetically adapt to become more tolerant of ocean acidification conditions, then evolutionary responses may play a role in the long-term dynamics of populations. This project examines how ocean acidification may alter patterns of natural selection for two species of fish in a set of breeding experiments that test tolerances to low pH of different genetic lineages. These experiments are determining the genetic capacity present in these populations to adapt to future conditions and offset the negative effects of changes in seawater chemistry. Broader impacts of this project include the training of two graduate students and at least nine undergraduates at an institution that is recognized as both a Hispanic Serving Institution and an Asian American, Native American, and Pacific Islander Serving Institution, and is one of the most culturally diverse universities in the world. Additional broader impacts include public outreach activities through local aquaria and regular meetings with local city and beach managers. Presentations focus on long-term population predictions of two fish species that are culturally and economically valuable.The goal of the project is to understand how ocean acidification will affect both offspring survival and maternal fitness. The project combines quantitative genetic studies with laboratory experiments and population modeling to examine tradeoffs between fecundity and offspring survival under present and predicted ocean acidification conditions. Breeding experiments are assessing the natural genetic variance underlying larval traits. The experimental protocol includes testing for parental effects by exposing adult fishes to high-pCO2 seawater during gametogenesis and measuring the survival of offspring experiencing conditions of ocean acidification. The capacity for genetic change in response to changes in ocean carbonate chemistry is being investigated through mathematical models. Quantitative evaluation includes 1) how selection operates as seawater chemistry changes; 2) levels of genetic (co)variation underlying larval traits; 3) whether non-genetic inheritance may affect responses to ocean acidification; and 4) whether evolutionary changes are fast enough to affect the dynamics of populations over relevant timeframes (e.g., 10-100 years). The project is developing a genetic model for describing how changes in ocean chemistry are driving natural selection.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.