Featured Research

from universities, journals, and other organizations

One law to rule them all: Sizes within a species appear to follow a universal distribution

Date:
March 4, 2013
Source:
EAWAG: Swiss Federal Institute of Aquatic Science and Technology
Summary:
Biologists have discovered what might be a universal property of size distributions in living systems. If valid throughout the animal kingdom, it could have profound implications on how we understand population dynamics of large ecosystems.

Four protist species, exhibiting different sizes.
Credit: Image courtesy of EAWAG: Swiss Federal Institute of Aquatic Science and Technology

Swiss Researchers at Eawag and EPFL discovered what might be a universal property of size distributions in living systems. If valid throughout the animal kingdom, it could have profound implications on how we understand population dynamics of large ecosystems.

Related Articles


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 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 or 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 Florian Altermann, the ecologist in the team. 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.


Story Source:

The above story is based on materials provided by EAWAG: Swiss Federal Institute of Aquatic Science and Technology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Andrea Giometto, Florian Altermatt, Francesco Carrara, Amos Maritan, Andrea Rinaldo. Scaling body size fluctuations. PNAS, March 2013 DOI: 10.1073/pnas.1301552110

Cite This Page:

EAWAG: Swiss Federal Institute of Aquatic Science and Technology. "One law to rule them all: Sizes within a species appear to follow a universal distribution." ScienceDaily. ScienceDaily, 4 March 2013. <www.sciencedaily.com/releases/2013/03/130304151652.htm>.
EAWAG: Swiss Federal Institute of Aquatic Science and Technology. (2013, March 4). One law to rule them all: Sizes within a species appear to follow a universal distribution. ScienceDaily. Retrieved March 27, 2015 from www.sciencedaily.com/releases/2013/03/130304151652.htm
EAWAG: Swiss Federal Institute of Aquatic Science and Technology. "One law to rule them all: Sizes within a species appear to follow a universal distribution." ScienceDaily. www.sciencedaily.com/releases/2013/03/130304151652.htm (accessed March 27, 2015).

Share This


More From ScienceDaily



More Plants & Animals News

Friday, March 27, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Jockey Motion Tracking Reveals Racing Prowess

Jockey Motion Tracking Reveals Racing Prowess

Reuters - Innovations Video Online (Mar. 26, 2015) Using motion tracking technology, researchers from the Royal Veterinary College (RVC) are trying to establish an optimum horse riding style to train junior jockeys, as well as enhance safety, health and well-being of both racehorses and jockeys. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Botswana Talks to End Illegal Wildlife Trade

Botswana Talks to End Illegal Wildlife Trade

AFP (Mar. 25, 2015) Experts are gathering in Botswana to try to end the illegal wildlife trade that is decimating populations of elephants, rhinos and other threatened species. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
Elephants Help Keep 18-Wheeler From Toppling Over

Elephants Help Keep 18-Wheeler From Toppling Over

Newsy (Mar. 25, 2015) The Natchitoches Parish Sheriff&apos;s Office discovered two elephants keeping a tractor-trailer that had gotten stuck in some mud upright on a highway. Video provided by Newsy
Powered by NewsLook.com
Baby 'pet' Orangutan Rescued from Chicken Cage Takes First Steps

Baby 'pet' Orangutan Rescued from Chicken Cage Takes First Steps

Reuters - Light News Video Online (Mar. 25, 2015) Buti, a baby orangutan who was left malnourished in a chicken cage before his rescue, takes his first steps after months of painful physical therapy. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins