. Earth Science News .
FLORA AND FAUNA
Genetic mutation trade-offs lead to parallel evolution
by Staff Writers
Chicago IL (SPX) May 26, 2017


This is a 3-D graph depicting evolutionary trajectories constrained by a phenotypic trade-off. Image by David T. Fraebel, U. of I. Department of Physics and Center for the Physics of Living Cells.

Organisms in nature adapt and evolve in complex environments. For example, when subjected to changes in nutrients, antibiotics, and predation, microbes in the wild face the challenge of adapting multiple traits at the same time. But how does evolution unfold when, for survival, multiple traits must be improved simultaneously?

While heritable genetic mutations can alter phenotypic traits and enable populations to adapt to their environment, adaptation is frequently limited by trade-offs: a mutation advantageous to one trait might be detrimental to another.

Because of the interplay between the selection pressures present in complex environments and the trade-offs constraining phenotypes, predicting evolutionary dynamics is difficult.

Researchers at the University of Illinois at Urbana-Champaign have shown how evolutionary dynamics proceed when selection acts on two traits governed by a trade-off. The results move the life sciences a step closer to understanding the full complexity of evolution at the cellular level.

Seppe Kuehn, an assistant professor of physics and member of the Center for the Physics of Living Cells at the U. of I., led the research. The team studied populations of the bacterium Escherichia coli, which can undergo hundreds of generations in a single week, providing ample opportunity to study mutations and their impact on heritable traits.

The team selected populations of E. coli for faster migration through a porous environment. A quantitative model revealed that populations could achieve the fastest migration by improving two traits at once - swimming speed and growth rate (cell division).

Kuehn explains, "This study sheds new light on how evolution proceeds when performance depends on two traits that are restricted by a trade-off. Though a mathematical model suggests that the fastest migrating populations should be composed of cells that swim fast and reproduce quickly, what we found was that populations achieve faster migration through two divergent evolutionary paths that are mutually exclusive: in other words, these populations improved in either swimming speed or reproduction rate, but not both."

David T. Fraebel, a U. of I. graduate student in Kuehn's lab group, is lead author on the study. He comments, "Most experiments apply selection pressure to optimize a single trait, and trade-offs are observed in this context due to decay of traits that aren't being selected rather than due to compromise between multiple pressures. We selected for swimming and growth simultaneously, yet E. coli was not able to optimize both traits at once."

The selection environment created by the team determined which evolutionary trajectory the populations followed. In a nutrient-rich medium, faster swimming meant slower reproduction; in a nutrient-poor environment, however, slower swimming and faster reproduction led to the same desired outcome: faster migration through the porous environment.

By sequencing the DNA of the evolved populations, the team identified the mutations responsible for adaptation in each condition. When they genetically engineered these mutations into the founding strain, these cells demonstrated faster migration and the same phenotypic trade-off as the evolved strains.

"Our results support the idea that evolution takes the direction that's genetically easy," says Kuehn. "In a nutrient-rich environment, it's easy to find a mutation that enables the cells to swim faster. In a nutrient-poor environment, it's easy to find a mutation that makes cell division faster. In both cases, the mutations are disrupting negative regulatory genes whose function it is to reduce gene expression or protein levels."

"Other recent studies have shown that microevolution is dominated by changes in negative regulatory elements. The reason: it's statistically easy to find a mutation that breaks things versus one that builds new function or parts.

When selection acts on two traits restricted by a trade-off, the phenotype evolves in the direction of breaking negative regulatory elements, because it's an easy path statistically. It relates to the availability of useful mutations."

Kuehn summarizes the finding's value: "Improving predictive modeling of evolution will involve understanding how mutations alter the regulation of cellular processes and how these processes are related to trade-offs that constrain traits. Uncovering the general principles that define the relationship between regulation and trade-offs could enable us to predict evolutionary outcomes."

These findings are published in the online journal eLife.

FLORA AND FAUNA
After 10-year gap, Thai lotuses bloom again
Prachuap Khiri Khan, Thailand (AFP) May 19, 2017
For the first time in a decade a Thai lake has given up its dazzling secret - the pink blooms of tens of thousands of lotuses. The sea of colour in Khao Sam Roi Yot national park, three hours south of Bangkok, is a show-stopping feat of nature that has locals hoping for a tourist bonanza. But it has also sparked warnings over the fragility of the environment with park rangers pleading w ... read more

Related Links
University of Illinois College of Engineering
Darwin Today At TerraDaily.com


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


Comment using your Disqus, Facebook, Google or Twitter login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

FLORA AND FAUNA
UN braces for up to 200,000 Iraqis to flee Mosul

Why civilian deaths in Iraq and Syria are increasing

Airbus Foundation and Airbus BizLab seek innovative concepts for humanitarian challenges

Witnesses to trauma can develop irrational fears

FLORA AND FAUNA
One-dimensional crystals for low-temperature thermoelectric cooling

New theory predicts wetted area of droplets colliding with flat surface

Physicists discover mechanism behind granular capillary effect

Collecting real-time data for material microstructural evolution during radiation exposure

FLORA AND FAUNA
Researchers untangle causes of differences in East Coast sea level rise

LA lawns use 70 billion gallons of water a year

Great Barrier Reef bleaching worse than first thought

How X-rays helped to solve mystery of floating rocks

FLORA AND FAUNA
Methane seeping from Arctic seabed may have an upside

NASA's Arctic Ecosystem Science Flights Begin

Elevation could help explain why Antarctica is warming slower than Arctic

China says no mining planned in Antarctica

FLORA AND FAUNA
In China, maggots finish plates, and food waste

Bordeaux pins hopes for ravaged vineyards on June bloom

Bordeaux pins hopes for ravaged vineyards on June bloom

Helping plants pump iron

FLORA AND FAUNA
Study explains severity of 9.2 magnitude Sumatra earthquake

Sri Lanka deploys thousands of troops as flood toll climbs to 169

Expect above-average Atlantic hurricane season, US forecasters say

Sri Lanka deploys more troops as flood toll climbs to 180

FLORA AND FAUNA
Biafra's military veterans: no regrets, 50 years on

Africa, so close yet so far from G7 summit

Rwanda to control presidential candidates' social media use

Nigeria seizes illegal arms shipment

FLORA AND FAUNA
New hypothesis about the origin of humankind suggests oldest hominin lived in Europe

Portions of human skeletal structure were established millions of years earlier than previously thought,

Study reveals architecture of the 'second brain,' the enteric nervous system

'Moral enhancement' technologies are neither feasible nor wise









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.