Bacterial 'ropes' tie down shifting Southwest

November 16, 2009

Researchers from Arizona State University have discovered that several species of microbes (cyanobacteria), at least one found prominently in the deserts of the Southwest, have evolved the trait of rope-building to lasso shifting soil substrates.

These tiny filamentous cyanobacteria are typically found in the environment as multicellular single strands or threads. Though known as pioneers in the biostabilization of soils, scientists have long puzzled over the factors that control and promote the twisting of some species' individual threads into thick cords sometimes inches in length.

Ferran Garcia-Pichel and Martin Wojciechowski, researchers in ASU's School of Life Sciences in the College of Liberal Arts and Sciences, examined genetic markers of rope-makers, relating them to shear stress, soil particle size and friction velocity (linked to erosion) to develop an understanding about the relationship between bacterial behavior, evolutionary fitness and environmental effectors.

The results of their study, published Nov. 17 in the journal Public Library of Science (PLoS) ONE, revealed that rope-building cyanobacteria, typically found in fine, sandy desert soils, marine subtidal stromatolites and coastal sand flats, are able, because of their larger size, to hog-tie sand grains and resist eroding wind and fluid at velocities that would typically wash away their thread-like relatives.

"While forming thick ropes seems to have apparent disadvantages, such as limiting access to light or nutrients, bundling-up actually turns out to be, literally, like throwing your neighbor a life-line," Garcia-Pichel says.

Wojciechowski adds: "These microbes rope-building attributes have added to their success as the true Western pioneers."

Garcia-Pichel believes that it was environmental effectors that led to the selection of genetic traits to promote rope-building. Phylogenetic analyses performed by the researchers have further shown that the evolution of the trait occurred separately in three different genera; an example of convergent evolution, rather than a tie to a single common rope-building ancestor.

In the desert, the initial stabilization of topsoil by rope-builders promotes colonization by a multitude of other microbes. From their interwoven relationships arise complex communities known as "biological soil crusts," important ecological components in the fertility and sustainability of arid ecosystems.
-end-


Arizona State University

Related Evolution Articles from Brightsurf:

Seeing evolution happening before your eyes
Researchers from the European Molecular Biology Laboratory in Heidelberg established an automated pipeline to create mutations in genomic enhancers that let them watch evolution unfold before their eyes.

A timeline on the evolution of reptiles
A statistical analysis of that vast database is helping scientists better understand the evolution of these cold-blooded vertebrates by contradicting a widely held theory that major transitions in evolution always happened in big, quick (geologically speaking) bursts, triggered by major environmental shifts.

Looking at evolution's genealogy from home
Evolution leaves its traces in particular in genomes. A team headed by Dr.

How boundaries become bridges in evolution
The mechanisms that make organisms locally fit and those responsible for change are distinct and occur sequentially in evolution.

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Paleontology: Experiments in evolution
A new find from Patagonia sheds light on the evolution of large predatory dinosaurs.

A window into evolution
The C4 cycle supercharges photosynthesis and evolved independently more than 62 times.

Is evolution predictable?
An international team of scientists working with Heliconius butterflies at the Smithsonian Tropical Research Institute (STRI) in Panama was faced with a mystery: how do pairs of unrelated butterflies from Peru to Costa Rica evolve nearly the same wing-color patterns over and over again?

Predicting evolution
A new method of 're-barcoding' DNA allows scientists to track rapid evolution in yeast.

Insect evolution: Insect evolution
Scientists at Ludwig-Maximilians-Universitaet (LMU) in Munich have shown that the incidence of midge and fly larvae in amber is far higher than previously thought.

Read More: Evolution News and Evolution Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.