Putative extremely long evolutionary stasis in bacteria might be explained by serial convergence

Abstract

In a recent paper, Schopf et al. (1) analyzed 1.8-Ga-old fossil sulfur bacteria and found an intriguing morphological similarity between fossil and modern species. Moreover, the authors showed that the deep-water sulfur cycling environment, where these bacteria reside, has not significantly changed throughout time. Thus, the authors hypothesize that this phenomenon is a result of an extreme evolutionary stasis in these bacteria. Such a static evolution is termed hypobradytelic and it has also been described in some cyanobacteria (2), where an evolutionary stasis is expected to be more than 2 Ga. However, these conclusions rely only on geological and morphological evidence. We feel …