Researchers studied genome sequences of nine environmentally adapted strains of E. coli phenotypically and taxonomically indistinguishable from typical E. coli. They found that commensal genomes for E. coli encode for more functions important for fitness in the human gut than typical E. coli and do not exchange genetic material with their environmental counterparts, and thus do not evolve according to the proposed fragmented speciation model.
The data support a more stringent and ecologic definition for bacterial species than the current definition, according to the authors. They suggest developing a new approach for defining distinctive phenotypes for new species.
Read the Proceedings of the National Academy of Sciences of the United States of America abstract.
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