This is the finding of a Franco-German study. The scientists investigated water frog populations in France and Northern Spain and noticed that the marsh frog (Rana ridibunda), which normally occurs only in Eastern Europe, has the potential to crowd out indigenous species like Graf’s hybrid frog (Rana grafi) and the Iberian water frog (Rana perezi).
The scientists believe this ability is related to the fact that the marsh frog lives longer and grows faster than the indigenous species. In addition, the female marsh frogs produce more progeny than their competitors, the researchers write in the scientific journal Comptes Rendus Biologies. The marsh frog has now spread from Central Asia as far as France and Spain. This latest spread is attributed to imports of live animals for culinary purposes. As the foreign species mix with the indigenous species, the indigenous water frogs are being pushed back into just a few areas. Imports of invasive species by humans are regarded as one of the main threats to species diversity on earth, alongside climate change.
Most stable marsh frog populations in France and Switzerland originated from frogs bred for gourmet restaurants or imported directly from various source countries. The frog fauna along larger river flood plains in both countries has now altered significantly in favour of the new frog species. Until now though, it was not clear why the new species had been able to establish themselves in the face of the indigenous species. The team of scientists investigated over 700 water frogs from 22 locations in the Rhone drainage basin in France and four locations in the Ebro drainage basin in Spain. "We noticed that the introduced marsh frog has a high competitive potential, particularly in high-oxygen, low-salinity freshwater. In these conditions the indigenous frogs hardly stand a chance," declares Dr Dirk Schmeller of the Helmholtz Centre for Environmental Research (UFZ). The displacement process is linked to the fact that the marsh frog grows faster than the indigenous frogs, and is in direct competition for food. In addition, female marsh frogs live longer and are more fertile. This means that over the course of their lives they produce significantly more progeny, thereby crowding out the other frog species.The number of progeny is increased still further because when the marsh frog mates with Graf’s hybrid frog (Rana grafi) or the edible frog (Rana esculenta), it produces marsh frog progeny. This may sound astounding, but can be attributed to a special type of reproduction called hybridogenesis, which is a special feature of water frog reproduction. All these factors may lead to the extinction of the indigenous water frog species, the researchers believe, and therefore recommend that the spread of the marsh frog be closely monitored.
Tilo Arnhold | EurekAlert!
Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
07.12.2016 | Earth Sciences
07.12.2016 | Earth Sciences
07.12.2016 | Materials Sciences