The old adage — “What doesn’t kill you makes you stronger” — seems to apply to salamanders evolving to survive in contaminated environments near roads. Yale University researcher Steven Brady compared
salamanders breeding in roadside ponds with those breeding in woodland ponds, and he found that the roadside salamanders have a tough life. Only 56 percent of salamander eggs in roadside ponds survive the first 10 weeks, compared with an 87 percent survival rate for salamander eggs in woodland ponds. The roadside salamanders also experience higher mortality, grow at a slower rate, and are more likely to develop L-shaped spines and other disfigurements — all likely linked to roadside contaminants, especially concentrations of salt. Still, Brady found that when he transferred eggs from roadside ponds and woodland ponds to a neutral environment, the roadside eggs out-survived those of their forest cousins. “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,” said Brady, whose study was published in the journal Scientific Reports.
Steven Brady/Yale University