Bacteria emit substantial rates, though they seem to avoid the mass extinction that has struck greater forms of life on Earth, according to new research from the University of British Columbia (UBC), Caltech and Lawrence Berkeley National Laboratory. This finding contradicts the widely held scientific thesis that microbe taxa rarely die due to their very large populations.
The study published today in Nature Ecology and Evolution used massive DNA sequencing and big-data analysis
"Bacteria rarely petrify, so we know very little about how the microbial Landscape has evolved over time, "says Stilianos Louca, a researcher at UBC's Biodiversity Research Center, which led the study. "Sequencing and math helped us fill the bacterial pedigree, map it over time, and expose it to extinction."
Louca and his colleagues estimate that between 1
"Although modern bacterial diversity is undoubtedly high, this is only a small part of diversity. Evolution has shaped Earth's history," says Louca.
Despite the frequent, steady extinction of individual species, the work shows that bacteria generally diversify exponentially without interruption. And they have avoided the abrupt, planet-wide mass extinctions that have occurred periodically between plants and animals. Louca suggests that competition between bacterial species drives the high rate of microbial death and makes them less prone to sudden mass extinction.
Former speciation and extinction events leave a complex trace in phylogenies – mathematical structures that encode evolutionary relatedness between existing bacterial species.
"This study would not have been possible 10 years ago," says Michael Doebeli, mathematician and zoologist UBC, and senior author on the paper. "Today's availability of extensive sequencing data and powerful computational resources enabled us to perform the complex mathematical analysis."
Next, Louca and his colleagues want to find out how the physiological properties of bacteria evolve over time, and whether their ecological diversity also increases as their taxonomic diversity has increased. If true, that would mean that even ancient and relatively simple organisms like bacteria still have the potential to find new ways to survive.