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Marine Viruses Could Unlock Mysteries of Evolution

Scientists study viral genomes important to reading Earth’s evolutionary history

VIRGINIA KEY, FLA. (Apr. 29, 2008) — In a collaborative paper published in a recent issue of the journal Nature, Dr. Pamela Reid, associate professor of Marine Geology and Geophysics at the UM Rosenstiel School of Marine and Atmospheric Science, was part of a team of scientists reporting on the genetic variability of viruses in living examples of Earth’s earliest reefs. The scientific team found that bacteriophages in modern microbialites (reefs built by microbes) in three distinct locations, Highborne Cay, Bahamas, and Pozas Azules II and Rio Mesquites, Mexico, were unique from one another and other known phage genomes worldwide. This finding suggests a potential lineage with ancient reef-building communities.

Viruses, and more specifically phages, are the most abundant living organisms in the world’s oceans. Phages influence microbial growth rates, genetic exchange, diversity and adaptation, and thus, evolution.

Unlike populations of bacteria and archaea, which may be highly localized in distribution, analysis of viral communities from four major ocean regions has shown that essentially all marine viruses are spread widely throughout the oceans.Moreover, phages from soil, sediments and fresh water can infect marine microbes, thereby effectively moving viruses between terrestrial and aquatic environments.

Dr. Reid and collaborators were therefore excited to discover that percent of the viral communities in the microbialites from Bahamas and Mexico showed almost no overlap between sites or with other viruses worldwide.  “The findings are truly significant,” said Reid.  “They suggest that modern microbialites are indeed windows into the past, which can help us to understand the functioning and evolution of ancient ecosystems.”

Microbialitesfirst appeared in the geological record 3.5 billion years ago, and for more than 2 billion years they are the main evidence of life on Earth. Whether modern microbialites are proxies of ancient ecosystems has been a major outstanding question.

The paper, “Biodiversity and biogeography of phages in modern stromatolites and thrombolites” incorporates results from Reid’s larger study of stromatolites at Highborne Cay, Bahamas where she and others have been conducting research for more than ten years. Stromatolites are microbialites with a distinct layered structure; thrombolites, in contrast, have a clotted internal structure.

Reid is the project leader for the Research Initiative on Bahamian Stromatolites and Principal Investigator of an ongoing, five year, NSF-supported project: “Biocomplexity of Modern Marine Stromatolites: Biogeochemical Cycling, Population Dynamics and Mineral Formation in a Three-Billion Year Old Ecosystem,” which involves 15 senior investigators from ten research institutions in the U.S. and Europe. The results from the metagenomic study of virsuses in Highborne Cay stromatolites will be integrated with genetic analyses of other microbial groups to define fundamental relationships between microbial populations, processes and products in one of Earth’s oldest ecosystems.

About the Rosenstiel School
Founded in the 1940’s, the University of Miami's Rosenstiel School of Marine & Atmospheric Science has grown into one of the world's premier marine and atmospheric research institutions. Offering dynamic interdisciplinary academics, the Rosenstiel School is dedicated to helping communities to better understand the planet, participating in the establishment of environmental policies, and aiding in the improvement of society and quality of life.  For more information, please visit www.rsmas.miami.edu