Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Young Salamanders' Movement Over Land Helps Stabilize Populations

31.03.2010
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:
http://www.umd.edu
http://chemlife.umd.edu/news/posts/2053

More articles from Life Sciences:

nachricht Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY

nachricht NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Global study of world's beaches shows threat to protected areas

19.07.2018 | Earth Sciences

New creepy, crawly search and rescue robot developed at Ben-Gurion U

19.07.2018 | Power and Electrical Engineering

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>