Featured Research

from universities, journals, and other organizations

Great exaptations: Most traits emerge for no crucial reason, scientists find

Date:
July 15, 2013
Source:
Santa Fe Institute
Summary:
By simulating changes in an organism's metabolism, scientists have now shown that most traits may emerge as non-crucial "exaptations" rather than as selection-advantageous adaptations.

Feathers did not originate for flight but may have helped insulate or waterproof dinosaurs before helping birds fly.
Credit: EcoView / Fotolia

Exactly how new traits emerge is a question that has long puzzled evolutionary biologists. While some adaptations develop to address a specific need, others (called "exaptations") develop as a by-product of another feature with minor or no function, and may acquire more or greater uses later. Feathers, for example, did not originate for flight but may have helped insulate or waterproof dinosaurs before helping birds fly.

Related Articles


How common such pre-adaptive traits are in relation to adaptive traits is unclear. Santa Fe Institute External Professor Andreas Wagner and colleague Aditya Barve, both evolutionary biologists at the University of Zurich, decided to get a systematic handle on how traits originate by studying all the chemical reactions taking place in an organism's metabolism.

Starting with the metabolism of an E. coli that can survive on glucose as its sole carbon source, they subjected the complex metabolic chemical process to a "random walk" through the set of all possible metabolisms, adding one reaction and deleting another from it with each step. They kept constant the total number of reactions and the bacterium's ability to survive on glucose alone, but allowed everything else to change. Every few thousand steps they analyzed the altered metabolism's reactions.

They found that most metabolisms were viable on about five other carbon sources -- sugars, building blocks of DNA or RNA, or proteins -- that are naturally common but chemically distinct compounds. To be certain that viability on these other carbon sources wasn't a natural consequence of viability on glucose, they tested metabolisms starting with viability on 49 other carbon sources, and each time found that exaptations emerged allowing the metabolism to survive on any one of several other carbon sources alone.

"We observed an incredible abundance of viability on carbon sources that these metabolisms were never even required to use," Wagner says.

By varying the number of reactions in a metabolic system, the team also found a relationship between the system's complexity (determined by number of reactions) and the extent of the exaptations, with larger networks having more of them.

The findings underscore the idea that traits we see now -- even complex ones, like color vision -- may have had neutral origins that sat latent for generations before spreading through populations, Wagner says.

"Our work shows that exaptations exceed adaptations several-fold," he says.

If exaptations are pervasive in evolution, he adds, it becomes difficult to distinguish adaptation from exaptation, and it could change the way evolutionary biologists think about selective advantage as the primary driver of natural selection.


Story Source:

The above story is based on materials provided by Santa Fe Institute. Note: Materials may be edited for content and length.


Journal Reference:

  1. Aditya Barve, Andreas Wagner. A latent capacity for evolutionary innovation through exaptation in metabolic systems. Nature, 2013; DOI: 10.1038/nature12301

Cite This Page:

Santa Fe Institute. "Great exaptations: Most traits emerge for no crucial reason, scientists find." ScienceDaily. ScienceDaily, 15 July 2013. <www.sciencedaily.com/releases/2013/07/130715134424.htm>.
Santa Fe Institute. (2013, July 15). Great exaptations: Most traits emerge for no crucial reason, scientists find. ScienceDaily. Retrieved November 26, 2014 from www.sciencedaily.com/releases/2013/07/130715134424.htm
Santa Fe Institute. "Great exaptations: Most traits emerge for no crucial reason, scientists find." ScienceDaily. www.sciencedaily.com/releases/2013/07/130715134424.htm (accessed November 26, 2014).

Share This


More From ScienceDaily



More Fossils & Ruins News

Wednesday, November 26, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Classic Hollywood Memorabilia Goes Under the Hammer

Classic Hollywood Memorabilia Goes Under the Hammer

Reuters - Entertainment Video Online (Nov. 26, 2014) The iconic piano from "Casablanca" and the Cowardly Lion suit from "The Wizard of Oz" fetch millions at auction. Sara Hemrajani reports. Video provided by Reuters
Powered by NewsLook.com
3D Map of Antarctic Sea Ice to Shed Light on Climate Change

3D Map of Antarctic Sea Ice to Shed Light on Climate Change

Reuters - Innovations Video Online (Nov. 24, 2014) A multinational group of scientists have released the first ever detailed, high-resolution 3-D maps of Antarctic sea ice. Using an underwater robot equipped with sonar, the researchers mapped the underside of a massive area of sea ice to gauge the impact of climate change. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Ruins Thought To Be Port Actually Buried Greek City

Ruins Thought To Be Port Actually Buried Greek City

Newsy (Nov. 24, 2014) Media is calling it an "underwater Pompeii." Researchers have found ruins off the coast of Delos. Video provided by Newsy
Powered by NewsLook.com
Amphipolis Tomb Architraves Reveal Faces

Amphipolis Tomb Architraves Reveal Faces

AFP (Nov. 22, 2014) Faces in an area of mosaics is the latest find by archaeologists at a recently discovered tomb dating back to fourth century BC and the time of Alexander the Great in Greece. Duration: 01:05 Video provided by AFP
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