New study shows lizard habitat could shrink by 48 percent
Climate change is likely to have a big impact on lizards across the United States, researchers warned in a recent paper after studying how warmer temperatures will affect them at all stages of their development.
The scientists found that lizard embryos die when subjected to a temperature of 110 degrees Fahrenheit even for a few minutes. Previous studies may have underestimated the impacts because they didn’t look closely at early life stages, when lizards are immobile and cannot seek shade or cool off when their surrounding soil becomes hot.
“Lizards put all of their eggs in one basket, so a single heat wave can kill an entire group of eggs,” said Ofir Levy, lead investigator of the study and postdoctoral fellow with the Arizona State University School of Life Sciences. “If mothers don’t dig deeper nests to lay their eggs, we expect this species to decline throughout the United States.”
The findings appeared online in the journal Proceedings of the Royal Society B.
The study used a climate model to predict how often heat waves in the past and future would kill developing lizards. Areas in the U.S. reaching lethal temperatures, even in the shade, could spread from 3 percent currently to 48 percent of the country in the next century.
Female lizards lay eggs in spring and summer, digging nests and then leaving their offspring to develop for more than two months. Mothers may choose shadier soils or dig deeper nests to help their offspring avoid the heat. But even if lizards lay eggs in cooler places, nests may still exceed the temperatures that embryonic lizards can tolerate.
And, assuming that baby lizards could reach the surface after hatching from a deeper nest, that still may not offer enough protection. Repeated exposure to above average, but not lethal temperatures, can negatively affect a lizard’s physiology and behavior.
“Since this year promises to be the hottest on record, we are asking whether organisms, like lizards, can adjust to their warming world,” said Michael Angilletta, professor and senior sustainability scientist with ASU School of Life Sciences. “It’s critical that we acquire detailed knowledge about what temperatures these lizards and other animals can tolerate throughout the life cycle, not just as adults.”
Levy added: “Because lizards are prey for animals such as birds, snakes and mammals, the harmful effects of climate change on embryonic lizards could also negatively affect other species.”