Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Research elucidates fundamental ecological concept

20.12.2019

An international team of scientists completes longest known predator-prey time series. Publication in Nature provides insight into ecological mechanisms.

Predator-prey cycles are among the fundamental phenomena of ecological systems: the population sizes of predators and their prey, for instance foxes and hares, are frequently subject to regular oscillations.


The rotifer Brachionus calyciflorus.

Foto: Guntram Weithoff

In a long-term experiment, an international team of researchers led by Prof. Dr. Bernd Blasius from the University of Oldenburg observed these oscillations in rotifer and unicellular algae populations across 50 cycles - a record period of time for this kind of study.

In an article published in the current issue of the scientific journal Nature, the researchers report that although there were brief periods when the regular oscillations in the two populations were interrupted by random swings, they always returned to their normal rhythm on their own.

“Our experiments confirm the theoretical concept of self-generated predator-prey cycles," says lead author Blasius, who heads the Mathematical Modelling group at the University of Oldenburg’s Institute for Chemistry and Biology of the Marine Environment (ICBM).

Predator-prey cycles are based on a feeding relationship between two species: if the prey species rapidly multiplies, soon afterwards the number of predators increases - until the predators eventually eat so many prey that the prey population goes down again. Soon afterwards, predator numbers likewise decrease due to starvation. This in turn leads to a rapid increase in the prey population – and a new cycle begins.

To predict such oscillations, scientists use simple mathematical models according to which populations of predator and prey species can theoretically coexist indefinitely. But the question of how long these cyclical fluctuations last in real-life communities had not been clarified: in field conditions, such oscillations frequently extend over a period of several years, so biologists have mainly relied on experiments with short-lived species.

In previous experiments, however, one of the two species died out after a few oscillations or the oscillations gradually disappeared. This led to the assumption that in real life, predator-prey cycles do not last on their own over extended periods of time, but are driven by an external factor, for example seasonal fluctuations in the food supply.

To clarify this question, Blasius and his colleagues from the University of Potsdam and McGill University in Canada brought together Brachionus calyciflorus, a planktonic rotifer species that occurs in fresh water , and unicellular green algae in experimental containers.

This system allowed the researchers to define continuous external conditions, for example a constant amount of nutrients for the algae. In the experiments, which were carried out at the University of Potsdam, the rotifers were the predators and the green algae the prey. As in other predator-prey relationships, a constant cycle was established: algae numbers fluctuated over a period of 6.7 days, as did rotifer numbers – but with a time lag of about 40 hours.

The researchers observed the two populations over a period of approximately one year, which corresponded to more than 50 oscillations and about 300 generations of rotifers. They ran several trials and produced time series representing a total of about 2000 measurement days.

“We chose organisms that reproduce quickly so that we would be able to produce multiple predator-prey cycles in a relatively short amount of time,” says co-author Prof. Dr. Gregor Fussmann, a biologist from the McGill University in Canada. “It still took us more than ten years to accumulate the experimental evidence necessary to make our point.”

Using modern data analysis methods, the team observed various oscillations in the system and determined the time sequence of these oscillations. Blasius and his team observed for example that the life stages of the rotifers (egg, sexually mature, and dead) also fluctuated periodically.

"We mainly observed regular oscillations in the predator and prey populations recurring at almost constant intervals," says Blasius. "Unexpectedly, however, these regular oscillations were repeatedly interrupted by short, irregular periods without any discernible external influences," Blasius explained.

During these periods, rotifer and algae numbers continued to fluctuate, but the team was unable to observe a fixed time span between the fluctuations. After a short time, however, the original sequence was automatically re-established. The researchers were able to reproduce similar alterations in their mathematical models: "They are proof of the resilience of the ecological system, in other words the ability to independently return to the original state after random disruptions," Blasius says.

The researchers’ analysis also demonstrates that the predator-prey cycle is based on a regular sequence of different processes in the ecological community. In the study, the team presents a mathematical method, a kind of fingerprint, for determining these regular processes in other oscillating biological systems. With this method it is possible for example to identify interactions between different species and cyclic or seasonal sequences in complex sets of data, the researchers say.

Wissenschaftliche Ansprechpartner:

Prof. Dr. Bernd Blasius, Tel.: 0441/798-3997, E-Mail: blasius@icbm.de

Originalpublikation:

B. Blasius, L. Rudolf, G. Weithoff, U. Gaedke, G.F. Fussmann: “Long-term cyclic persistence in an experimental predator-prey system” Nature (2019), doi 10.1038/s41586-019-1857-0

Weitere Informationen:

https://uol.de/en/icbm/mathematical-modelling

Dr. Corinna Dahm-Brey | idw - Informationsdienst Wissenschaft

Further reports about: Brachionus calyciflorus green algae oscillations rotifers

More articles from Life Sciences:

nachricht How decisions unfold in a zebrafish brain
16.01.2020 | IMP - Forschungsinstitut für Molekulare Pathologie GmbH

nachricht Neuromuscular organoid: It’s contracting!
16.01.2020 | Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fraunhofer IAF establishes an application laboratory for quantum sensors

In order to advance the transfer of research developments from the field of quantum sensor technology into industrial applications, an application laboratory is being established at Fraunhofer IAF. This will enable interested companies and especially regional SMEs and start-ups to evaluate the innovation potential of quantum sensors for their specific requirements. Both the state of Baden-Württemberg and the Fraunhofer-Gesellschaft are supporting the four-year project with one million euros each.

The application laboratory is being set up as part of the Fraunhofer lighthouse project »QMag«, short for quantum magnetometry. In this project, researchers...

Im Focus: How Cells Assemble Their Skeleton

Researchers study the formation of microtubules

Microtubules, filamentous structures within the cell, are required for many important processes, including cell division and intracellular transport. A...

Im Focus: World Premiere in Zurich: Machine keeps human livers alive for one week outside of the body

Researchers from the University Hospital Zurich, ETH Zurich, Wyss Zurich and the University of Zurich have developed a machine that repairs injured human livers and keep them alive outside the body for one week. This breakthrough may increase the number of available organs for transplantation saving many lives of patients with severe liver diseases or cancer.

Until now, livers could be stored safely outside the body for only a few hours. With the novel perfusion technology, livers - and even injured livers - can now...

Im Focus: SuperTIGER on its second prowl -- 130,000 feet above Antarctica

A balloon-borne scientific instrument designed to study the origin of cosmic rays is taking its second turn high above the continent of Antarctica three and a half weeks after its launch.

SuperTIGER (Super Trans-Iron Galactic Element Recorder) is designed to measure the rare, heavy elements in cosmic rays that hold clues about their origins...

Im Focus: LZH’s MOMA laser ready for the flight to Mars

One last time on Earth it has been turned on in France in December 2019. The next time the MOMA laser developed by the Laser Zentrum Hannover e.V. (LZH) is going into operation will be on Mars. The ExoMars rover into which the laser is integrated has now successfully passed the thermal vacuum tests at Airbus in Toulouse, France.

For 18 days the ExoMars rover Rosalind Franklin was subjected to thermal vacuum tests at Airbus. There, it had to withstand strong changes in temperature and...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Decontaminating pesticide-polluted water using engineered nanomaterial and sunlight

16.01.2020 | Process Engineering

MOSHEMT—innovative transistor technology reaches record frequencies

16.01.2020 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>