Transient Darwinian selection in Salmonella enterica serovar Paratyphi A during 450 years of global spread of enteric fever
Abstract
The most recent common ancestor of Paratyphi A, one of the most common causes of enteric fever, existed approximately 450 y ago, centuries before that disease was clinically recognized. Subsequent changes in the genomic sequences included multiple mutations and acquisitions or losses of genes, including bacteriophages and genomic islands. Some of those evolutionary changes were reliably attributed to Darwinian selection, but that selection was only transient, and many genetic changes were subsequently lost because they rendered the bacteria less fit (purifying selection). We interpret the history of Paratyphi A as reflecting drift rather than progressive evolution and suggest that most recent increases in frequencies of bacterial diseases are due to environmental changes rather than the novel evolution of pathogenic bacteria.
- Publication:
-
Proceedings of the National Academy of Science
- Pub Date:
- August 2014
- DOI:
- 10.1073/pnas.1411012111
- Bibcode:
- 2014PNAS..11112199Z