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Thriving Hybrid Salamanders Contradict Common Wisdom
September 27, 2007E-mail this story
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Thriving Hybrid Salamanders Contradict Common Wisdom
September 25, 2007
A new UC Davis study not only has important findings for the future of California tiger salamanders, but also contradicts prevailing scientific thought about what happens when animal species interbreed.
The study, by former UC Davis doctoral student Benjamin Fitzpatrick (now on the faculty of University of Tennessee, Knoxville) and professor Bradley Shaffer, was published recently in the Proceedings of the National Academy of Sciences' online edition.
The salamander experts studied the survival rates and genetic makeup of three types of salamanders: native California tiger salamanders (Ambystoma californiense), which are protected under the U.S. Endangered Species Act; barred tiger salamanders that were introduced in California from Texas in the 1950s (Ambystoma tigrinum mavortium); and the hybrid offspring born when the two species mated.
They found that more of the hybrid young survived in the wild than did young of the native or the introduced species -- quite a surprise, since animal hybrids are usually less fit than their parents ("hybrid vigor" is largely limited to plant crosses).
That raises difficult questions for managing endangered native salamander populations, Shaffer said. Some conservationists might say that hybrids are an acceptable change, since they are favored by natural selection, and "improve" the original species. Others might consider hybrids to be genetically impure and regard them as threats to the native salamanders, their competitors and their prey.
Such questions will arise more frequently, Shaffer said, as humans both create new opportunities for hybridization with introduced species, and improve the genetic analyses that detect them.
The study, titled "Hybrid vigor between native and introduced salamanders raises new challenges for conservation," was funded by the U.S. Environmental Protection Agency (EPA), National Science Foundation (NSF), U.S. Department of Agriculture, CALFED Bay-Delta Program, and UC Davis Agricultural Experiment Station.
UC Davis graduate programs in ecology and evolutionary biology are among the best in the nation, and were ranked first in 2007 by U.S. News & World Report.
UC Davis
The study, by former UC Davis doctoral student Benjamin Fitzpatrick (now on the faculty of University of Tennessee, Knoxville) and professor Bradley Shaffer, was published recently in the Proceedings of the National Academy of Sciences' online edition.
The salamander experts studied the survival rates and genetic makeup of three types of salamanders: native California tiger salamanders (Ambystoma californiense), which are protected under the U.S. Endangered Species Act; barred tiger salamanders that were introduced in California from Texas in the 1950s (Ambystoma tigrinum mavortium); and the hybrid offspring born when the two species mated.
They found that more of the hybrid young survived in the wild than did young of the native or the introduced species -- quite a surprise, since animal hybrids are usually less fit than their parents ("hybrid vigor" is largely limited to plant crosses).
That raises difficult questions for managing endangered native salamander populations, Shaffer said. Some conservationists might say that hybrids are an acceptable change, since they are favored by natural selection, and "improve" the original species. Others might consider hybrids to be genetically impure and regard them as threats to the native salamanders, their competitors and their prey.
Such questions will arise more frequently, Shaffer said, as humans both create new opportunities for hybridization with introduced species, and improve the genetic analyses that detect them.
The study, titled "Hybrid vigor between native and introduced salamanders raises new challenges for conservation," was funded by the U.S. Environmental Protection Agency (EPA), National Science Foundation (NSF), U.S. Department of Agriculture, CALFED Bay-Delta Program, and UC Davis Agricultural Experiment Station.
UC Davis graduate programs in ecology and evolutionary biology are among the best in the nation, and were ranked first in 2007 by U.S. News & World Report.
UC Davis
Salamander Current Events and Salamander News RSSResearchers discover mechanism that helps humans see in bright and low light
Ever wonder how your eyes adjust during a blackout? When we go from light to near total darkness, cells in the retina must quickly adjust. Vision scientists at Washington University School of Medicine in St. Louis have identified an intricate process that allows the human eye to adapt to darkness very quickly. The same process also allows the eye to function in bright light.
Pitt research suggests EPA pesticide exposure test too short, overlooks long term effects
The four-day testing period the U.S. Environmental Protection Agency (EPA) commonly uses to determine safe levels of pesticide exposure for humans and animals could fail to account for the toxins' long-term effects, University of Pittsburgh researchers report in the September edition of Environmental Toxicology and Chemistry.
Spring fishing season arrives... and with it, amphibian diseases
Waterdogs, they're called, these larvae of tiger salamanders used as live bait for freshwater fishing.
Scientists document salamander decline in Central America
The decline of amphibian populations worldwide has been documented primarily in frogs, but salamander populations also appear to have plummeted, according to a new study by University of California, Berkeley, biologists.
10 new amphibian species discovered in Colombia
Scientists today announced the discovery of 10 amphibians believed to be new to science, including a spiky-skinned, orange-legged rain frog, three poison dart frogs and three glass frogs, so called because their transparent skin can reveal internal organs.
Stanford researchers: Global warming is killing frogs and salamanders in Yellowstone Park
Frogs and salamanders, those amphibious bellwethers of environmental danger, are being killed in Yellowstone National Park. The predator, Stanford researchers say, is global warming.
Weizmann Institute scientists discover how an injured embryo can regenerate itself
More than 80 years have passed since the German scientist Hans Spemann conducted his famous experiment that laid the foundations for the field of embryonic development.
A missing link settles debate over the origin of frogs and salamanders
The description of an ancient amphibian that millions of years ago swam in quiet pools and caught mayflies on the surrounding land in Texas has set to rest one of the greatest current controversies in vertebrate evolution. The discovery was made by a research team led by scientists at the University of Calgary.
Salamanders, headwater streams critical in food chain
University of Missouri scientist Ray Semlitsch studies creatures most people don't ever see. These creatures are active only at night and thrive in the shallow, cool, wet surroundings of headwater streams, an oft-overlooked biological environment.
Ancient Amphibians Left Full-Body Imprints
Unprecedented fossilized body imprints of amphibians have been discovered in 330 million-year-old rocks from Pennsylvania. The imprints show the unmistakably webbed feet and bodies of three previously unknown, foot-long salamander-like critters that lived 100 million years before the first dinosaurs.
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