( ry of the core of the bacterial cell. T...)Map of life on Earth could be used on Mars

Jumping genes

Jumping genes may be a headache for researchers, but they serve an important ecological purpose, helping other organisms to succeed in their habitats, and can illuminate trait development across the tree of life.

"We try to construct the core with gene sequences, and then we look at the distribution of traits such as those involved in metabolism by laying it onto the tree," she said.

Timely appearances of certain traits among prokaryotes on the tree of life can betray a trend of habitat divergence, facilitated by lateral gene transfer. The emergence of traits corresponding to measurable changes in the known geologic record allow researchers to date organisms with relative certainty. Blank can then use chronological data to analyze niche specialization, "where these organisms like to grow," among members of each life domain over geologic time.

Habitat divergence among bacteria is consistent with patterns of divergence among the other prokaryotes, Blank's research shows. She notes a pervasive trend of cyanobacterial organisms diverging from low-salinity environments into marine environments over time.

"We have the ancestral Archeae ?it diverges into two major lineages, the Crenarchaeota and the Euryarchaeota, one which grows in marine environments, the other on continents, " Blank said. "They grow and diverge for perhaps a billion years, and then they start colonizing each other's environments. The marine Euryarchaeota eventually colonize the terrestrial environments and the Crenarchaeota colonize the marine environments. My point is that it could have taken a very long time for them to come back and to form even more complex ecosystems. So the literal interpretation of these patterns is that early habitat specialization could have lasted for a billion years."

Afte
'"/>

Source:Washington University in St. Louis