About

Dawn Y. Sumner is a professor whose research focuses on microbial mats and microbialite structures, particularly in extreme environments such as Antarctic lakes. Her work involves characterizing microbial communities and their interactions with geochemical processes, including photosynthesis and nutrient cycling. Sumner's research extends to understanding ancient microbial ecosystems, with applications to both Earth and Mars sedimentary records. She mentors a diverse group of postdoctoral scholars, graduate students, and undergraduates, guiding projects that explore microbial diversity, sedimentology, and biogeochemical cycling in modern and ancient settings. Her lab investigates the phylogenetic and metabolic structures of benthic microbial mats, the origin of photosynthesis, and the preservation of microbial biosignatures, contributing to the broader understanding of early life and its environmental context.

Research topics

• Genetics
• Biology
• Computational biology
• Computer Science
• Evolutionary biology
• Ecology
• Geochemistry
• Geology
• Astrobiology
• Data science
• Botany
• Geomorphology
• World Wide Web
• Library science
• Astronomy

Selected publications

• The Use of Microbialite and Fossil Samples to Introduce Astrobiology to K-12th Grade Students While Aligning with the Next Generation Science Standards

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• Evidence of Burrowing Affecting the Morphology of Oncoids from the Lower-Middle Cambrian Carrara Formation

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• Using Micro X-Ray Computed Tomography Scanning to Characterize Carbonate Precipitation in Lake Fryxell, Antarctica

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Morphology and Distribution of Bubble‐Supported Microbial Mats From Ice‐Covered Antarctic Lakes

  Journal of Geophysical Research Biogeosciences · 2025-03-01 · 4 citations

  articleOpen accessSenior author

  Abstract Gas bubbles directly influence the macromorphology of benthic microbial mats resulting in preservable biosedimentary structures. This study characterizes the morphology and distribution of microbial mats growing in gas‐supersaturated, perennially ice‐covered lakes Fryxell, Joyce, and Hoare of the McMurdo Dry Valleys of Antarctica. Photosynthetic benthic mats within the gas‐supersaturated zone trap oxygen‐rich bubbles and become buoyant, tearing off the bottom as “liftoff mats.” These liftoff mats form a succession of morphologies starting with bubble‐induced deformation of flat mats into tent, ridge, and finger liftoff mat. With progressive deformation, mats tear, forming sheet liftoff, while multiple cycles of deformation and tearing transform sheet into strip liftoff. Some mats detach from the substrate and float to the underside of the ice. The depth range of the liftoff zone has varied over time at each lake. Downslope expansion of bubble formation brings previously bubble‐free, deep‐water pinnacle mats into the liftoff zone. When the liftoff zone shallows, liftoff mats at the deeper end deflate and can become scaffolding for additional mat growth. The superposition and relative orientation of liftoff and pinnacle mats can be used to track the maximum depth of the liftoff zone and changes in gas saturation state in these lakes through time. Our results demonstrate that gas bubbles, even when they are transitory, can exert a significant impact on the morphology of microbial mats at larger scales. This provides a way to identify similar structures and gas supersaturated environments in the biosedimentary record.

  PublisherOA PDFDOI

• Influencia de madrigueras en la morfologia de oncoides de la Formacion Carrara del Cámbrico Temprano y Medio

  Abstracts with programs - Geological Society of America · 2025-01-01

  articleSenior author
  PublisherDOI

• ENGAGING WITH K-12TH GRADE STUDENTS WITH GEOSCIENCES THROUGH THE USE OF ACTIVITIES THAT ALIGN WITH THE NEXT GENERATION SCIENCE STANDARDS

  Abstracts with programs - Geological Society of America · 2025-01-01

  article
  PublisherDOI

• Physiology, Not Nutrient Availability, May Have Limited Primary Productivity After the Emergence of Oxygenic Photosynthesis

  Geobiology · 2024-09-01 · 4 citations

  articleOpen accessSenior author

  The evolution of oxygenic photosynthesis in Cyanobacteria was a transformative event in Earth's history. However, the scientific community disagrees over the duration of the delay between the origin of oxygenic photosynthesis and oxygenation of Earth's atmosphere, with estimates ranging from less than a hundred thousand to more than a billion years, depending on assumptions about rates of oxygen production and fluxes of reductants. Here, we propose a novel ecological hypothesis that a geologically significant delay could have been caused by biomolecular inefficiencies within proto-Cyanobacteria-ancestors of modern Cyanobacteria-that limited their maximum rates of oxygen production. Consideration of evolutionary processes and genomic data suggest to us that proto-cyanobacterial primary productivity was initially limited by photosystem instability, oxidative damage, and photoinhibition rather than nutrients or ecological competition. We propose that during the Archean era, cyanobacterial photosystems experienced protracted evolution, with biomolecular inefficiencies initially limiting primary productivity and oxygen production. Natural selection led to increases in efficiency and thus primary productivity through time. Eventually, evolutionary advances produced sufficient biomolecular efficiency that environmental factors, such as nutrient availability, limited primary productivity and shifted controls on oxygen production from physiological to environmental limitations. If correct, our novel hypothesis predicts a geologically significant interval of time between the first local oxygen production and sufficient production for oxygenation of environments. It also predicts that evolutionary rates were likely highly variable due to strong environmental selection pressures and potentially high mutation rates but low competitive interactions.

  PublisherOA PDFDOI

• Manganese-rich sandstones as an indicator of ancient oxic lake water conditions in Gale crater, Mars

  2024-05-01

  reportOpen access

  Manganese has been observed on Mars by the NASA Curiosity rover in a variety of contexts and is an important indicator of redox processes in hydrologic systems on Earth. Within the Murray formation, an ancient primarily fine-grained lacustrine sedimentary deposit in Gale crater, Mars, have observed up to 45× enrichment in manganese and up to 1.5× enrichment in iron within coarser grained bedrock targets compared to the mean Murray sediment composition. This enrichment in manganese coincides with the transition between two stratigraphic units within the Murray: Sutton Island, interpreted as a lake margin environment, and Blunts Point, interpreted as a lake environment. On Earth, lacustrine environments are common locations of manganese precipitation due to highly oxidizing conditions in the lakes. Here, we explore three mechanisms for ferromanganese oxide precipitation at this location: authigenic precipitation from lake water along a lake shore, authigenic precipitation from reduced groundwater discharging through porous sands along a lake shore, and early diagenetic precipitation from groundwater through porous sands. All three scenarios require highly oxidizing conditions and we discuss oxidants that may be responsible for the oxidation and precipitation of manganese oxides. This work has important implications for the habitability of Mars to microbes that could have used Mn redox reactions, owing to its multiple redox states, as an energy source for metabolism.

  PublisherOA PDFDOI

• Metagenome-assembled bacterial genomes from benthic microbial mats in ice-covered Lake Vanda, Antarctica

  Microbiology Resource Announcements · 2024-04-08 · 2 citations

  articleOpen access

  ABSTRACT We recovered 57 bacterial metagenome-assembled genomes (MAGs) from benthic microbial mat pinnacles from Lake Vanda, Antarctica. These MAGs provide access to genomes from polar environments and can assist in culturing and utilizing these Antarctic bacteria.

  PublisherDOI

• Genomic profiles of four novel cyanobacteria MAGs from Lake Vanda, Antarctica: insights into photosynthesis, cold tolerance, and the circadian clock

  Frontiers in Microbiology · 2024-01-11 · 4 citations

  articleOpen accessSenior author

  Cyanobacteria in polar environments face environmental challenges, including cold temperatures and extreme light seasonality with small diurnal variation, which has implications for polar circadian clocks. However, polar cyanobacteria remain underrepresented in available genomic data, and there are limited opportunities to study their genetic adaptations to these challenges. This paper presents four new Antarctic cyanobacteria metagenome-assembled genomes (MAGs) from microbial mats in Lake Vanda in the McMurdo Dry Valleys in Antarctica. The four MAGs were classified as Leptolyngbya sp. BulkMat.35, Pseudanabaenaceae cyanobacterium MP8IB2.15, Microcoleus sp. MP8IB2.171, and Leptolyngbyaceae cyanobacterium MP9P1.79. The MAGs contain 2.76 Mbp – 6.07 Mbp, and the bin completion ranges from 74.2–92.57%. Furthermore, the four cyanobacteria MAGs have average nucleotide identities (ANIs) under 90% with each other and under 77% with six existing polar cyanobacteria MAGs and genomes. This suggests that they are novel cyanobacteria and demonstrates that polar cyanobacteria genomes are underrepresented in reference databases and there is continued need for genome sequencing of polar cyanobacteria. Analyses of the four novel and six existing polar cyanobacteria MAGs and genomes demonstrate they have genes coding for various cold tolerance mechanisms and most standard circadian rhythm genes with the Leptolyngbya sp. BulkMat.35 and Leptolyngbyaceae cyanobacterium MP9P1.79 contained kaiB3 , a divergent homolog of kaiB .

  PublisherOA PDFDOI

Recent grants

• Evolution of Oxygenic Photosynthesis as Preserved in Melainabacterial Genomes from Lake Vanda, Antarctica

  NSF · $324k · 2018–2022

Frequent coauthors

• N. Mangold

  Laboratoire de Planétologie et Géosciences

  137 shared

• J. P. Grotzinger

  California Institute of Technology

  112 shared

• S. Maurice

  Institut de Recherche en Astrophysique et Planétologie

  101 shared

• O. Forni

  97 shared

• O. Gasnault

  Institut de Recherche en Astrophysique et Planétologie

  91 shared

• K. M. Stack

  Jet Propulsion Laboratory

  81 shared

• Stéphane Le Mouëlic

  Université d'Angers

  79 shared

• A. Cousin

  Centre National de la Recherche Scientifique

  78 shared

Education

• Ph.D., Earth, Atmospheric, and Planetary Sciences

  Massachusetts Institute of Technology

  1995

• B.Sc., Geological and Planetary Sciences

  California Institute of Technology

  1989

Awards & honors

• Fellow of the American Association for the Advancement of Sc…
• California Academy of Sciences Academy Fellow, 2020
• Distinguished Career Award, Geobiology and Geomicrobiology D…
• Geological Society of America Fellow, 2014