How a species stays relevant as it changes its world

Dec 19, 2013 by John German

How complexity evolved in cells is a question as intriguing as it is difficult to explain. Though we cannot fully solve the puzzle, we can learn how species give themselves time to go from random to programmed development.

A new study published today in PLOS ONE reveals an optimal switching rate between forms of a species as it makes its environment less livable.

"If you're a bacterium in a beaker, just by the process of growing and dividing, you're changing the environment into one that no longer favors you," explains Eric Libby, an SFI Omidyar Fellow who specializes in mathematical . "You then have two options. One, go extinct. Two, throw off a mutant that's adapted to the new environment."

To see how a species adjusts to the conditions it creates, Libby and colleague Paul Rainey at the New Zealand Institute for Advanced Study looked to Pseudomonas fluorescens. The free-living bacterium has two forms: the smooth type proliferates in a broth, but by doing so uses up the oxygen. A single mutation produces the second wrinkly type, which makes a glue that sticks offspring together.

The resulting bacterial mat rises to the surface – the only place oxygen is available in a beaker choked by the smooth type. (Conversely, as the mat grows and provides stable access to oxygen, wrinkly types randomly produce smooth types.) Eventually the mat collapses, letting oxygen stream back into the broth.

Based on this simple life cycle, the researchers ran simulations where P. fluorescens drove the environment between two states, one favorable for either population type, to see at what switching rates the species flourished. The results surprised them.

"The best strategy is to produce the kind that's not good in the current environment about 10 percent of the time," says Libby. That rate is independent of environmental factors and is three orders of magnitude higher than the researchers expected. Further, letting some of both types survive through an environment switch also led to a surprising response: one organism will thrive, nearly driving the other to oblivion, then will suddenly collapse and die.

Libby reasons that these findings suggest that a simple relationship between organisms and environments could provide a possible route for the evolution of developmental programs from random mutation-driven change.

Explore further: Top Japan lab dismisses ground-breaking stem cell study

More information: Libby E, Rainey. "Eco-Evolutionary Feedback and the Tuning of Proto-Developmental Life Cycles." PLoS ONE (2013) 8(12): e82274. DOI: 10.1371/journal.pone.0082274

add to favorites email to friend print save as pdf

Related Stories

Environmental complexity promotes biodiversity

Sep 17, 2013

A new study published in the journal American Naturalist helps explain how spatial variation in natural environments helps spur evolution and give rise to biodiversity.

Recommended for you

Top Japan lab dismisses ground-breaking stem cell study

22 hours ago

Japan's top research institute on Friday hammered the final nail in the coffin of what was once billed as a ground-breaking stem cell study, dismissing it as flawed and saying the work could have been fabricated.

Research sheds light on what causes cells to divide

Dec 24, 2014

When a rapidly-growing cell divides into two smaller cells, what triggers the split? Is it the size the growing cell eventually reaches? Or is the real trigger the time period over which the cell keeps growing ...

Locking mechanism found for 'scissors' that cut DNA

Dec 24, 2014

Researchers at Johns Hopkins have discovered what keeps an enzyme from becoming overzealous in its clipping of DNA. Since controlled clipping is required for the production of specialized immune system proteins, ...

Scrapie could breach the species barrier

Dec 24, 2014

INRA scientists have shown for the first time that the pathogens responsible for scrapie in small ruminants (prions) have the potential to convert the human prion protein from a healthy state to a pathological ...

Extracting bioactive compounds from marine microalgae

Dec 24, 2014

Microalgae can produce high value health compounds like omega-3s , traditionally sourced from fish. With declining fish stocks, an alternative source is imperative. Published in the Pertanika Journal of Tr ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.