Warming Causes Salamanders to Lose Their Stripes
Red-backed salamanders in eastern North America have responded to warming temperatures by losing their namesake red stripe. Over the last century, the proportion of salamanders sporting a red dorsal stripe declined by 6%. At the same time, temperatures across the salamander's range climbed by 0.7 °C (1.3 °F).
Salamanders of the species Plethodon cinereus have either a bright red stripe running from head to tail, or a plain black back. Striped salamanders aren't just distinctively marked. They're also genetically predisposed to living in cooler temperatures.
Compared with striped salamanders, plain ones don't survive as well in cold, take cover earlier in fall, and have a lower metabolic rate. The red form of red-backed salamanders is more common at higher elevations and the northern parts of its range, where conditions are cooler.
The black form comprised 20% of all red-backed salamanders in the early 1900s. By 2004, 26% of the red-backed salamander population lacked a red back. A warming trend is selecting for salamanders without a stripe.
Scientists from State University of New York who discovered the decline in red backs figure that even more than regional climatic warming, changes in forest cover are spurring the color shift.
Red-backed salamanders typically live among the logs and leaf litter of woodland floors. Most of the original forests in the salamander's range, including Illinois, Indiana and Pennsylvania, were logged over the last 300 years. After old growth forests are cleared, a site's soil can warm by several degrees.
James P. Gibbs, Nancy E. Karraker. 2006. Effects of Warming Conditions in Eastern North American Forests on Red-Backed Salamander Morphology. Conservation Biology. 20(3): 913-917.