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.

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 July 22, 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 July 22, 2014).

Share This




More Fossils & Ruins News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) — Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? Video provided by Newsy
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) — As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 Video provided by AFP
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) — Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
45 Years Later, Buzz Aldrin on Walking on Moon

45 Years Later, Buzz Aldrin on Walking on Moon

AP (July 18, 2014) — Forty-five years ago Sunday, Apollo 11's Neil Armstrong and Buzz Aldrin became the first humans to set foot on the moon. Speaking at the Intrepid Sea, Air & Space Museum, Aldrin described what he was thinking right before the historic walk. (July 18) Video provided by AP
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:
from the past week

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