Academic journal article The Science Teacher

Headline Science

Academic journal article The Science Teacher

Headline Science

Article excerpt

Salamanders Adapt to Toxic Ponds

Spotted salamanders exposed to contaminated roadside ponds are adapting to their toxic environments, according to a Yale University study published in Scientific Reports. The study provides the first documented evidence that a vertebrate can adapt to the negative effects of roads by evolving rapidly.

Salamanders breeding in roadside ponds are exposed to a host of contaminants from road runoff. Chief among these is sodium chloride from road salt, which reaches average concentrations 70 times higher than in woodland ponds located several hundred feet from the road.

"While the evolutionary consequences of roads are largely unknown, we know they are strong agents of natural selection and set the stage for fast evolution," says Steven Brady, the study's author and a doctoral student at the Yale School of Forestry and Environmental Studies. "These animals are growing up in harsh environments where they face a cocktail of contaminants, and it appears that they are evolving to cope with them."

Brady found that salamanders in roadside ponds have higher mortality, grow more slowly, and are more than likely to develop L-shaped spines and other disfigurements. In roadside ponds, only 56% of salamander eggs survive the first 10 weeks of development, whereas 87% survive in woodland ponds. As roadside ponds become more toxic, the surviving salamanders may develop a genetic advantage over their counterparts living in woodland ponds.

The salamanders that survive year after year in the roadside ponds appear to have adapted to the harsh conditions. "The animals that come from roadside ponds actually do better--substantially better--than the ones that originate from woodland ponds when they're raised together," Brady says.


Animals adapting to human activities is not new. For example, fish have begun to mature at smaller sizes in response to commercial fishing. But whereas humans directly use fish for consumption, salamanders are just bystanders to human activities. This suggests that the majority of species, which are not specifically targeted for human use, may be experiencing profound evolutionary consequences. And it appears that even species not being driven to extinction--and seldom thought about--are changing.


"This adaptation is certainly encouraging for conservation," says Brady. "But our modern footprint is fundamentally changing species in ways we don't understand and, critically, we don't know if these adaptive responses will keep pace with environmental change."

Brady observed the development of the salamanders in 10 ponds--five roadside and five woodland--in Yale Myers Forest and in Willington, Connecticut. The paper, "Road to Evolution? Local Adaptation to Road Adjacency in an Amphibian (Ambystoma maculatum)" is available online. (Yale University)

Stormy Space Weather

A potent solar flare on January 27, 2012, occurring just days after the Sun launched the biggest coronal mass ejection (CME) seen in nearly a decade, delivered a powerful radiation punch to Earth's magnetic field even though it was aimed away from our planet.

According to University of New Hampshire (UNH) scientists, this was due to both the existing population of energetic particles launched by the first CME and a powerful magnetic connection that reeled particles toward Earth from the Sun's blast region, which had spun to an oblique angle.

"Energetic particles can sneak around the 'corner,' as was the case in Friday's event when it was launched at the Sun's limb, or edge," says astrophysicist Harlan Spence, director of the UNH Institute for the Study of Earth, Oceans, and Space (EOS) and principal investigator for the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument onboard NASA's Lunar Reconnaissance Orbiter (LRO) mission. …

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