Collaborative Research: EAGER: Developing tools to assess the evolutionary implications of partial clonality in alpine snow algae

Many globally important processes like carbon cycling and human disease dynamics are a result of microscopic eukaryotes. Yet our understanding of evolutionary processes across the entire tree of life is limited due to the inherent challenges of studying microscopic taxa. Tools developed for macroscopic, and often obligately sexually reproducing, species are often not tractable in microbes where generation times are short, population sizes large, and extracting DNA from individual cells difficult.

Further, population-level ecology and evolutionary biology research have focused on species that can be grown in the lab; yet, only ~1% of microbes can be cultured. This proposal focuses on the snow algae, a group of closely related, single-celled algae that turn seasonal snow packs pink or red. The aim is to develop novel single-cell population genetic protocols to study these threatened organisms and sentinels of environmental change.

Thousands of cells from inter- and intra-annual Chlainomonas-dominated blooms in the Cascade Range of the United States will be genotyped. A goal is to understand how environmental factors (e.g., nitrogen) influence snow algal reproduction. The project will support two graduate students.

The three PIs will integrate data into classroom-based and field-based curriculum for university-level students and share data with the public through social media and peer-reviewed publications.

This project uses snow algae to develop new methods for studying the population genetics of microbial eukaryotes from natural populations. The work will provide novel and critical techniques for studying reproductive modes that will be broadly applicable across microbial systems. Two novel elements are proposed: (1) combining single-cell isolation methods with state-of-the-art multilocus genotyping, and (2) using a novel microbial eukaryotic system (snow algae) with features making the method development tractable.

Reproductive mode data will be generated and combined with measurements of (i) the ploidy of cells and (ii) environmental conditions to ascertain whether limited nitrogen initiates sexual reproduction. The approach is radically different compared to traditional microalgal population genetics that rely on lab-based cultures, raising questions of how representative those data are in nature.

This proposal fits the EAGER funding mechanism as the single-cell population genetic methods are high risk-high payoff and should be readily transferable to other systems.

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.