RAPID: Ecological Reversal of Evolutionary Trends During a Climate Anomaly: Plasticity, Adaptation, and Integration of Environmental Change into Genomic and Organismal Architecture

University Of California - Merced, Merced CA

Investigators

Abstract

This project seeks to understand the factors that lead to dramatic changes in the appearance of jellyfishes following the most recent extreme El Niño perturbation on record. The project will then examine the consequences of these changes in morphology for the jellyfish, its symbiont, and the prey of the jellyfish. Intriguingly, the changes in appearance of the jellyfishes mirror changes seen during the 15,000 years since the Last Glacial Maximum. The temporary nature of the rare perturbation generates considerable urgency to study this unanticipated natural event. Comparison of current perturbed and subsequent "normal" conditions, and comparisons with an ancestor-like sister population in the ocean, has the potential to rapidly advance understanding of interactions between an organism's genotype and phenotype, and its environment in both ecological and evolutionary contexts. The project will train a graduate student in integrative biology, improve understanding of a socio-economically important ecosystem, supporting decisions by local government resource managers, and improve understanding of plasticity in jellyfish which may contribute to, and shape, the consequences of jellyfish blooms. Results will be incorporated into education and outreach materials for a new hybrid online general education course. Ecophenotypic variation of Mastigias medusae that is associated with dramatic changes in abiotic environment and population size in Jellyfish Lake associated with a severe El Niño mirrors evolutionary trends seen among populations inhabiting a suite of marine lakes and adjacent ocean locations in Palau. This project will sample and describe key environmental and organismal details of this extreme perturbation, enabling examination of how environmental changes interact with differential expression and/or selection of loci to amend functional phenotypic variation on ecological and evolutionary time-scales. Methods include measurement of morphological and behavioral phenotypes of Mastigias medusae at two time-points presenting each of two characteristic morphologies; tissue sampling from those phenotypically distinct medusae for genomic, epigenetic, and transcriptomic analyses; stable isotope analyses; microbiome analyses; and characterization of abiotic and biotic characteristics of the environment, including temperature, salinity, oxygen, pH, water clarity, nutrients, chl a, bacterioplankton, phytoplankton, and zooplankton. Comparable data will be collected in an ancestor-like sister population (subspecies) from the adjacent ocean. These measurements will reveal whether similar suites of loci are involved in plastic and in adaptive responses to changing environments, i.e. whether there is support for the concept of genetic assimilation in Mastigias. They will also inform the understanding of organismal responses to gradual and rapid climate change globally, and will generate novel hypotheses regarding variation in homologous structures across the scyphozoan tree of life.