Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Young Salamanders' Movement Over Land Helps Stabilize Populations

Amphibians—frogs, toads, salamanders, and newts—are disappearing worldwide, but the stream salamanders of the Appalachian Mountains appear to be stable. This region is home to the largest diversity of salamanders in the world (more than 70 species reside here), and scientists want to understand what contributes to the stability of these salamander populations.

In research published in the March 29, 2010 issue of the Proceedings of the National Academy of Sciences, Dr. Evan Grant (a research associate in the University of Maryland Department of Biology and wildlife biologist with the US Geological Survey's Amphibian Research and Monitoring Initiative); along with Dr. William Fagan, University of Maryland Department of Biology; and collaborators James Nichols, US Geological Survey (USGS) Patuxent Wildlife Research Center; and Winsor Lowe, University of Montana; describe how two species of stream salamanders find new homes by moving both within streams and over land to adjacent streams during multiple life stages, and how this movement may help to stabilize their populations.

"Scientists tend to be more focused on populations that are declining or threatened," explains Grant, "but it is also important to look at the populations that are doing well, and to understand what makes the population or species more stable. You can apply this to interpret what might be happening with populations that are declining."

The Fagan lab is known for its expertise in combining math and biology to understand the spatial distribution of species to solve real-world conservation problems. They create mathematical models to understand patterns, influences and changes in spatial distribution.

Evan Grant, who is a wildlife biologist with the USGS Patuxent Wildlife Research Center and completed this work as part of his dissertation research, used observations of marked animals to estimate the dispersal probabilities of two species of lungless salamanders (Desmognathus fuscus and Desmognathus monticola) who reside in headwater streams (these salamanders are known to prefer the headwaters, where the stream originates) in Virginia's Shenandoah National Park.

These salamanders are aquatic as larva (a stage which lasts ~9 months), and then become terrestrial as juveniles, when they reabsorb their gills and begin to breathe by diffusing oxygen through their skin. While the stream is the best habitat for the salamanders because of the stable temperatures and humidity, both juvenile and adult salamanders can travel over land to forage for food, and occasionally move from one stream to another.

Over a two year period, Grant and colleagues captured and marked more than 2500 salamanders in three 40 meter segments along the headwater streams using a harmless injectable dye (known as a "visual implant elastomer"). They then released them and tracked their movements by recapturing them during four return visits each year, recording their location each time. This study was the first to track salamanders across all three life stages - larva, juvenile, and adult - because the research team overcame the difficulty in marking the larval salamanders, which are only a half an inch long. The adult salamanders of these two species grow to a length of almost four inches.

Grant used sophisticated models to estimate the probability of a salamander moving from one segment to another within the same stream either upstream or downstream, and from one stream to another by moving across land. What he found supported his prediction that the salamanders generally prefer to disperse upstream and that those in the juvenile stage were the most likely to change location by moving both upstream and overland to the adjacent stream.

"Marking the larvae was key to figuring out the movement ecology of the species, because once the larva transformed into a juvenile, that is when the dispersal happened," says Grant. "If I hadn't marked the larva and just marked the juveniles, the probability that I would have observed that dispersal would have been very, very slim."

It turns out that this overland movement is very important contributor to population stability. Grant used the observed dispersal probabilities to conduct a computer simulation to show changes in population stability across a range of extinction risk scenarios in the stream networks. He investigated how the combination of dispersal by the three possible movement routes - upstream, downstream, and over land - resulted in changes to predicted extinction times. His modeling showed that when even a small amount of overland movement occurred, it increased the likelihood of salamander population persistence dramatically. This was only the case under low to moderate rates of extinction risk. Under higher extinction probabilities (like we see in stream-breeding frogs in the neotropics), no amount of dispersal could stabilize populations.

These results suggest that the specific routes of dispersal play a big role in salamander population stability, and helps to explain why we have not seen declines in headwater stream salamander populations. This information can help wildlife biologists, amphibian conservationists, and resource managers in their efforts to maintain or restore salamander habitats to facilitate persistence of the species and prevent extinctions. These data confirm that the terrestrial habitat between streams is important to salamanders and must be maintained and protected.

Kelly Blake | EurekAlert!
Further information:

More articles from Life Sciences:

nachricht Strong, steady forces at work during cell division
20.10.2016 | University of Massachusetts at Amherst

nachricht Disturbance wanted
20.10.2016 | Max Delbrück Center for Molecular Medicine in the Helmholtz Association

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Innovative technique for shaping light could solve bandwidth crunch

20.10.2016 | Physics and Astronomy

Finding the lightest superdeformed triaxial atomic nucleus

20.10.2016 | Physics and Astronomy

NASA's MAVEN mission observes ups and downs of water escape from Mars

20.10.2016 | Physics and Astronomy

More VideoLinks >>>