One law to rule them all -- sizes within a species appear to follow a universal distribution

March 04, 2013

Flocks of birds, schools of fish, and groups of any other living organisms might have a mathematical function in common. Studying aquatic microorganisms, Andrea Giometto, a researcher EPFL and Eawag, showed that for each species he studied, body sizes were distributed according to the same mathematical expression, where the only unknown is the average size of the species in an ecosystem. His article was published in in PNAS in March 2013.

Several observations suggest that the size distribution function could be universal. Giometto made his observations in the lab on 14 species of aquatic microorganisms, including unicellular and multicellular ones that are very distant from an evolutionary point of view. The microorganisms he studied varied by four orders of magnitude, the difference in size between a mouse and an elephant.

Furthermore, the mathematical function describing the size distribution remained unchanged even when the species adapted to new environments - changes in water temperature, the presence of absence of competitors - by changing their average size.

Based on these observations, Giometto and his collaborators suggest that two separate factors work in tandem to shape the size distribution of a species. First, environmental factors influence the average size of a species. Second, physiological factors, or genetics, cause the observed variability of species sizes around the average size.

From species to communities

So far the focus has been on the size distribution of individuals of a single species. But Giometto's findings become particularly interesting in light of an observation that is well known to ecologists. "If you take a cup of water from the sea and analyze all of the microorganisms it contains, you find that in an ecological community no size tends to be over or underrepresented," says Andrea Giometto. Mathematically, the sizes can be described by a power-law distribution.

Taken together, these observations of size distributions within a species and within all the species in a given ecological community have interesting implications. If in an ecosystem several species begin to converge around the same size, a balancing force will kick in to restore the power-law distribution, either by acting on the abundance or size of each species.

If, as Giometto and his co-authors speculate, their observations are valid beyond the species they studied, they may provide additional evidence for the existence of universal laws that govern natural ecosystems. These laws would regulate not only the size and abundance of organisms in an ecosystem, but also other properties, such as the number of species that co-exist.

Finding power-laws and using them to describe complex systems already has a successful track record. "In physics, the observation that systems followed power-laws was instrumental in understanding phase transitions. We believe that power-laws can be similarly helpful to gain a deeper understanding of how systems of living matter work," says Giometto, a physicist, who is seeking to apply methods from his field to understand biological ecosystems.

Ecole Polytechnique Fédérale de Lausanne

Related Microorganisms Articles from Brightsurf:

A more resistant material against microorganisms is created to restore cultural heritage
The study was performed by a research team at the University Research Institute into Fine Chemistry and Nanochemistry at the University of Cordoba and Seville's Institute of Natural Resources and Agrobiology of the Spanish National Research Council

NYUAD study finds gene targets to combat microorganisms binding to underwater surfaces
A group of synthetic biologists at NYU Abu Dhabi (NYUAD) have identified new genetic targets that could lead to safe, biologically-based approaches to combat marine biofouling - the process of sea-based microorganisms, plants, or algae binding to underwater surfaces.

Less flocking behavior among microorganisms reduces the risk of being eaten
When algae and bacteria with different swimming gaits gather in large groups, their flocking behaviour diminishes, something that may reduce the risk of falling victim to aquatic predators.

Are vultures spreaders of microbes that put human health at risk?
A new analysis published in IBIS examines whether bacteria, viruses, and other microorganisms that are present in wild vultures cause disease in the birds, and whether vultures play a role in spreading or preventing infectious diseases to humans and other animal species.

Timing key in understanding plant microbiomes
Oregon State University researchers have made a key advance in understanding how timing impacts the way microorganisms colonize plants, a step that could provide farmers an important tool to boost agricultural production.

Advances in the production of minor ginsenosides using microorganisms and their enzymes
Advances in the Production of Minor Ginsenosides Using Microorganisms and Their Enzymes - BIO Integration Announcing a new article publication for BIO Integration journal.

Study shows how microorganisms survive in harsh environments
In northern Chile's Atacama Desert, one of the driest places on Earth, microorganisms are able to eke out an existence by extracting water from the rocks they colonize.

Microorganisms in parched regions extract needed water from colonized rocks
Cyanobacteria living in rocks in Chile's Atacama Desert extract water from the minerals they colonize and, in doing so, change the phase of the material from gypsum to anhydrite.

Verticillium wilt fungus killing millions of trees is actually an army of microorganisms
A research project studied the microbiome of olive tree roots and concluded that Verticillium wilt is fueled by a community of microorganisms that team up to attack plants, thus reassessing the way this problem is dealt with

New drug formulation could treat Candida infections
With antimicrobial resistance (AMR) increasing around the world, new research led by the University of Bristol has shown a new drug formulation could possibly be used in antifungal treatments against Candida infections.

Read More: Microorganisms News and Microorganisms Current Events 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