Climate change isolates Rocky Mountain butterflies

August 13, 2007

Expanding forests in the Canadian Rocky Mountains are slowly isolating groups of alpine butterflies from each other, which may lead to the extinction of the colourful insects in some areas, says a new study from the University of Alberta.

A rising tree line in the Rockies due to global warming, and a policy not to initiate "prescribed burns" (intentionally started, controlled fires) in order to manage forest growth, has created the tenuous condition for the alpine butterflies, said Jens Roland, a biological scientist at the University of Alberta.

The alpine Apollo butterfly (Parnassius) inhabits open meadows because they, like other types of butterflies, need sunlight to generate enough body heat in order to fly, and forests are generally too shady for them and inhibit their ability to move.

However, expanding forests are pinching off the Parnassius from their neighbors in nearby meadows.

"The risk of local extinction and inbreeding depression will increase as meadows shrink, the population sizes decrease and the populations become more isolated," Roland said.

"The gene pool of this species is getting more and more fragmented, and gene flow is reduced, which means these populations are more vulnerable," he added.

One particularly cold winter or summer season may be enough to wipe out an entire meadow of Parnassius, said Roland, who is the lead author of a paper on this research that appears today in the Proceedings of the National Academy of Sciences.

Roland also said the Parnassius are not currently a threatened species, but they and smaller species native to Rocky Mountain meadows, including some insects and rodents, will suffer "several consequences" if forests continue to expand unchecked.

"Often forest management practice is led by the needs of larger species, such as mountain sheep, elk and grizzly bears, while the interests of the smaller species, such as butterflies, are overlooked," he said.

Prescribed burns, which protect and create meadows and generally foster diversity in forests, are undertaken in the Canadian Rocky Mountain national parks but are rare outside of them, Roland said.

Roland has completed earlier studies that showed expanding forests are restricting Parnassius's movements in parts of the Rocky Mountains. He feels his latest study is a natural extension of his previous work.

"It's important to study movement among populations that are becoming more and isolated due to shrinking habitats; but, ultimately, we need to study the population dynamics to find out if the habitat allows the species to reproduce and persist," Roland said.

"This latest study shows that as populations function with less synchrony and become more independent of each other—as we've shown the Parnassius is becoming in certain areas in the Canadian Rockies—the local extinction rate of small populations will increase," he added.

Source: University of Alberta

Explore further: Restoring ocean health

Related Stories

Restoring ocean health

September 16, 2015

More than a decade ago, California established marine protected areas (MPAs) in state waters around the northern Channel Islands off the coast of Santa Barbara. Several years later, the National Oceanic and Atmospheric Administration ...

Preventing floods and erosion

August 19, 2015

California is on fire—again. About 130,000 acres have been scorched in more than 20 major fires actively burning in the state, according to the California Department of Forestry and Fire Protection. But the flames are not ...

Fossil study: Dogs evolved with climate change

August 18, 2015

Old dogs can teach humans new things about evolution. In Nature Communications a new study of North American dog fossils as old as 40 million years suggests that the evolutionary path of whole groups of predators can be a ...

Mysterious fungus killing snakes in at least nine states

August 9, 2015

Hidden on hillsides in a remote part of western Vermont, a small number of venomous timber rattlesnakes slither among the rocks, but their isolation can't protect them from a mysterious fungus spreading across the eastern ...

Recommended for you

Chimpanzees shed light on origins of human walking

October 6, 2015

A research team led by Stony Brook University investigating human and chimpanzee locomotion have uncovered unexpected similarities in the way the two species use their upper body during two-legged walking. The results, reported ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.