Project: Dimensions: Collaborative Research: Life at extremes: Linking the phylogenetic and genomic diversity of ctenophores to ecophysiological adaptations in the deep sea

The deep sea is more than 90 percent of the inhabitable space on Earth, yet life there is largely a mystery to science. Ctenophores, also known as comb jellies, are marine predators found in all oceans, inhabiting both deep and shallow seas. Although fragile and difficult to study, they are biologically important, in part because they appear to have been the first group of animals to split off from all other organisms during evolution, even before sponges and jellyfish. Over evolutionary time, many marine organisms have transitioned their home ranges to and from the deep sea despite the tremendous differences between these two habitats, including light, temperature, and hydrostatic pressure. Such habitat shifts required dramatic genetic and physiological changes to these animal lineages over time. The relationships between comb jelly species indicate that species from a variety of different families have evolved to live and thrive in the deep sea. This project will compare closely related deep and shallow species at biochemical, physiological and genetic levels to understand how these transitions came about. It will answer questions about the fundamental mechanisms of animal evolution and develop publicly available tools for analyzing genomic data sets. It will result in the training of cutting-edge techniques for two PhD students, a postdoc, two masters students, and numerous undergraduates. Public outreach involving biodiversity in the deep sea and gelatinous animals will help educate and inspire appreciation of marine life.

The main objective of this project is to understand evolution and diversification using cutting edge molecular analyses to investigate the deep-sea habitat as the generating force of novel biological adaptations. Ctenophore specimens will be collected using blue-water SCUBA in surface waters and remotely operated submarines in the deep sea to generate complementary physiological and genomic data across the full phylogenetic and functional diversity of ctenophores. With samples taken across a range of habitats from shallow tropical waters to temperate bathypelagic zone, the team will measure physiological capabilities and sequence transcriptomes and genomes. This project will develop novel algorithms to identify genes involved in depth adaptation and examine the genetic events that underlie physiological tolerances and adaptations to high hydrostatic pressures in the deep sea. To confirm the theory-based predictions of how gene sequence affects the properties of enzymes, proteins will be expressed and characterized in the lab. Collaborations between the students, postdocs and PIs involved in this project will substantially enhance an interdisciplinary workforce trained in both classical and cutting edge skills needed for contemporary biodiversity investigations.