Nav: Home

Diversity without limits

November 22, 2016

Bacteria were the original masters of their domain, having the Earth to themselves for the majority of their existence, filling every environmental niche, nook and cranny, from mountain peaks to the thermal vents at the ocean's floor.

Now, researchers at Temple and Oakland universities have completed a new tree of prokaryotic life calibrated to time, assembled from 11,784 species of bacteria. The new tree explores grand patterns of evolutionary change that, surprisingly, has revealed remarkable similarities with that of eukaryotes, including animals, plants, and fungi.

With widespread rapid and low-cost sequencing available, the branches in the tree of life have grown ever more detailed and scientists can more readily uncover macroevolutionary forces at work. Relying on data from the small subunit ribosomal RNA of bacteria, researchers at Temple University's Center for Biodiversity, including Laura H. Carnell Professor and director S. Blair Hedges and Postdoctoral Fellow Julie Marin, together with colleagues from Oakland University, Assistant Professor Fabia Battistuzzi and graduate student Anais Brown, produced a new timetree of prokaryotic life.

"We have produced a timetree of most described prokaryote species that has revealed a constant diversification rate, remarkably similar in that respect to eukaryotes and probably resulting from the same mechanism, the random nature of lineage survival over millions of years," said Hedges.

The findings, which appear in the advanced online edition of Molecular Biology and Evolution, build on a 2015 eukaryotic timetree study led by Hedges, which revealed that eukaryotic life has been expanding at a constant rate --- not slowing down. "Our results were contrary to the popular alternative model that predicts a slowing down of diversification as niches fill up with species," Hedges said.

Instead, the constant rate of diversification found in that 2015 study indicated that eukaryotic ecological niches are not being filled up and saturated. Those previous findings also underscored the importance of random genetic events and geographic isolation in speciation -- the biological process by which new species arise. The researchers in that study found that it took about 2 million years on average for a new eukaryotic species to emerge onto the scene.

Yet, in the new prokaryotic study, the rate of diversification was found to be 2.1 times slower than in eukaryotes. "This is probably the result of the periodic selection, which provides genetic cohesion of lineages, slowing their genetic divergence," said Marin. "The overall similarity in these important aspects of the evolution of prokaryotes and eukaryotes supports the idea that species of prokaryotes are real evolutionary units much like eukaryotic species."

The evolutionary implications of both studies are profound, indicating that the diversification of life on Earth as a whole is unbound by constraints. Rather, diversity results from the random splitting of lineages and is neither limited by existing diversity (filled niches) nor responsive, in any major way, to environmental changes.
-end-
The new prokaryotic data will be added the Timetree of Life (TTOL) initiative, which includes internet tools for researchers and the general public to explore the tree of life and its relationship with historical patterns in other fields such as geology, climatology, and astronomy.

Molecular Biology and Evolution (Oxford University Press)

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...