Collaborative Research: PurSUiT: Standing on the shoulders of giants: Phylogeny, systematics, and adaptation of marine epizoic diatoms to endangered megafaunal hosts

New York University, New York NY

Investigators

Abstract

Animals are covered in microbes. For example, the microbes in and on the human body number in the trillions, outnumbering our own cells. Sea turtles, whales, dolphins, and manatees represent some of our most cherished marine megafauna, and these, too, are covered in diverse microbes. These microbial communities are essential to protecting these animals from infections and disease and include bacteria and diatoms, a group of microscopic algae that produces 20% of Earth’s oxygen. Microbes represent most of Earth’s biodiversity, but most of these species are yet to be discovered. This project will document the diatom and bacterial species living on marine megafauna, describing and naming many new diatom species for the first time. Genome sequencing and characterization of the chemical environments will show how the diatoms are related to one another, how they move between host animals, and how they interact with bacteria to use the unique resources offered by their hosts. Since many of these diatoms reside only on threatened or endangered animal species, the fates of these microbial communities are tied to their hosts. The discoveries made through this project may allow researchers to grow these diatoms in the lab, creating a permanent living record should their hosts suffer extinction. The project will provide cross-disciplinary training for students, preparing them for jobs in industry or academia. A documentary film will introduce the complex microbial communities studied in this project to a general audience. Through this project, an estimated 50 diatom species will be documented and described, doubling the number of known epizoic diatom species. Genome sequencing of cultivable and uncultivable species will be used to place epizoic diatoms onto the broader diatom phylogeny, which will provide a framework to: (1) infer how many times free-living ancestors have colonized and diversified on animal hosts, (2) reveal patterns of host switching to discern epizoic generalist and specialist diatom species, and (3) characterize mechanisms of host specialization in one model lineage that speciated and underwent a radical trophic shift following a host transition. The broad phylogenomic framework, combined with complementary metagenomic, metatranscriptomic, and metabolomic profiles will reveal the role of host skin microbiome in shaping trophic strategies and other adaptive changes by diatoms, factors that likely combine to facilitate or constrain host switching and speciation on evolutionary timescales. 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.