Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Research demonstrates the influence of temporal niches in maintaining biodiversity

09.07.2013
By studying rapidly evolving bacteria as they diversify and compete under varying environmental conditions, researchers have shown that temporal niches are important to maintaining biodiversity in natural systems. The research is believed to be the first experimental demonstration of temporal niche dynamics promoting biodiversity over evolutionary time scales.

The temporal niches – changes in environmental conditions that occur during specific periods of time – promoted frequency-dependent selection within the bacterial communities and positive growth of new mutants. They played a vital role in allowing diversity among bacterial phenotypes to persist.

The research provides new insights into the factors that promote species coexistence and diversity in natural systems. Understanding the mechanisms governing the origin and maintenance of biodiversity is important to scientists studying the roles of both ecology and evolution in natural systems.

"This study provides the first experimental evidence showing the impact of temporal niche dynamics on biodiversity evolution," said Lin Jiang, co-author of the paper and an associate professor in the School of Biology at the Georgia Institute of Technology. "Our laboratory results in bacteria can potentially explain the diversity dynamics that have been observed for other organisms over evolutionary time."

The research, which was supported by the National Science Foundation, was scheduled to be published July 9 in the journal Nature Communications.

In experimental manipulation of the bacterium Pseudomonas fluorescens, the researchers showed that alternating environmental conditions in 24-hour cycles strongly influences biodiversity dynamics by helping to maintain closely-related phenotypes that might otherwise be lost to competition with a dominant phenotype. The experiment followed the bacteria through more than 200 generations over a period of nearly two weeks.

In the laboratory, Jiang and graduate student Jiaqi Tan established communities of the bacterium in test tubes called microcosms. In designing the experiments, they collaborated with Colleen Kelly, a senior research associate in the Department of Zoology at the University of Oxford.

"You begin with one phenotype, and within two days, you might have two or three different phenotypes," said Jiang. "The system can do this in a matter of days."

Through a 12-day experimental period, the researchers subjected one group of cultures to 24-hour periods in which they were alternately allowed to grow undisturbed and shaken vigorously. To control for the impact of starting conditions, cultures within those two groups were chosen to begin with a period of static growth, while others began with a period of shaken growth. Finally, groups of control cultures were grown under continuous shaking or continuous static conditions.

During the study, the researchers periodically measured the population sizes of each phenotype present in each culture. Cultures subjected to alternating shaking and static conditions produced the highest level of diversity among the closely-related bacteria, which is often studied because it diversifies so rapidly.

"Static conditions promoted diversification," Jiang explained. "But the shaking tended to maintain the diversity that had evolved. Both conditions were essential for high biodiversity."

In experiments, the ancestral bacterial phenotype, which is known as "smooth morph," quickly diversifies and generates two niche-specialists, known as "wrinkled spreader" and "fuzzy spreader." Those, in turn, diversify into additional phenotypes. Competition for oxygen in the microcosms in which the bacteria grow is believed to drive the diversification; shaking the microcosms changes the levels of oxygen available to each phenotype. Because different phenotype groups inhabit different sections of the container, the shaking eliminated the preferred niches of some phenotypes.

The diversification in the microcosms experiencing constant shaking was much slower than in static microcosms. In microcosms experiencing temporal niche dynamics – the alternating shaking and non-shaking periods – the diversity increased rapidly and was maintained longer than in the other environments. The researchers found that the two different temporal niche dynamics environments – which differed only in their starting conditions – both produced richer biodiversity than those environments without it.

While the diversification occurred rapidly over a period of four days, the decline in the number of phenotypes due to natural competition took longer. Some of the phenotypes were ultimately excluded through the competitive processes.

"Diversity typically increases with time, then plateaus," said Jiang. "Without temporal niche, diversity tends to decline. Temporal niche allows a greater diversity to be maintained over time than would be possible otherwise."

Though the study focused on rapidly diversifying bacteria, the researchers believe it may have broader implications. The general theory of temporal niche dynamics was developed with more complex organisms, such as plants and corals, in mind.

"The mechanisms that promote biodiversity, which we call frequency-dependent selection, are very common in species," said Tan. "As long as you have a strong intra-species competition within the populations, you are expected to see this frequency-dependent selection. Based on this most common mechanism that we find in this system, there are implications for other ecosystems."

For the future, the researchers would like to study the effects of combining spatial and temporal niches in evolution.

"From this experiment, we know that temporal niche can maintain biodiversity," said Tan. "Similarly, we want to manipulate spatial diversity to see if heterogeneity in the spatial scale can affect the maintenance of biodiversity."

This research was supported by the National Science Foundation under grants DEB-1120281 and DEB-1257858. Any opinions expressed are those of the authors and do not necessarily represent the official views of the National Science Foundation.

CITATION: Jiaqi Tan, Colleen K. Kelly and Lin Jiang, "Temporal niche promotes biodiversity during adaptive radiation," (Nature Communications, 2013). http://dx.doi.org/10.1038/ncomms3102

John Toon | EurekAlert!
Further information:
http://www.gatech.edu

More articles from Life Sciences:

nachricht What the world's tiniest 'monster truck' reveals
23.08.2017 | American Chemical Society

nachricht Treating arthritis with algae
23.08.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Researchers devise microreactor to study formation of methane hydrate

23.08.2017 | Materials Sciences

ShAPEing the future of magnesium car parts

23.08.2017 | Automotive Engineering

New insights into the world of trypanosomes

23.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>