text-only page produced automatically by LIFT Text Transcoder Skip all navigation and go to page contentSkip top navigation and go to directorate navigationSkip top navigation and go to page navigation
National Science Foundation
News
design element
News
News From the Field
For the News Media
Special Reports
Research Overviews
NSF-Wide Investments
Speeches & Lectures
NSF Current Newsletter
Multimedia Gallery
News Archive
News by Research Area
Arctic & Antarctic
Astronomy & Space
Biology
Chemistry & Materials
Computing
Earth & Environment
Education
Engineering
Mathematics
Nanoscience
People & Society
Physics
 

Email this pagePrint this page


Press Release 12-049
Early Spring Drives Butterfly Population Declines

"Ahead-of-time" snowmelt triggers chains of events in the Mormon Fritillary butterfly

Photo of a Mormon Fritillary butterfly feeding on an aspen fleabane daisy.

A Mormon Fritillary butterfly feeding on an aspen fleabane daisy, a main nectar source.
Credit and Larger Version

March 15, 2012

Early snowmelt caused by climate change in the Colorado Rocky Mountains snowballs into two chains of events: a decrease in the number of flowers, which, in turn, decreases available nectar. The result is decline in a population of the Mormon Fritillary butterfly, Speyeria mormonia.

Using long-term data on date of snowmelt, butterfly population sizes and flower numbers at the Rocky Mountain Biological Laboratory, Carol Boggs, a biologist at Stanford University, and colleagues uncovered multiple effects of early snowmelt on the growth rate of an insect population.

"Predicting effects of climate change on organisms' population sizes will be difficult in some cases due to lack of knowledge of the species' biology," said Boggs, lead author of a paper reporting the results online in this week's journal Ecology Letters.

Taking into account the butterfly's life cycle and the factors determining egg production was important to the research.

Butterflies lay eggs (then die) in their first summer; the caterpillars from those eggs over-winter without eating and develop into adults in the second summer.

In laboratory experiments, the amount of nectar a female butterfly ate determined the number of eggs she laid. This suggested that flower availability might be important to changes in population size.

Early snowmelt in the first year leads to lower availability of the butterfly's preferred flower species, a result of newly developing plants being exposed to early-season frosts that kill flower buds.

The ecologists showed that reduced flower--and therefore nectar--availability per butterfly adversely affected butterfly population growth rate.

Early snowmelt in the second year of the butterfly life cycle worsened the effect, probably through direct killing of caterpillars during early-season frosts.

The combined effects of snowmelt in the two consecutive years explained more than four-fifths of the variation in population growth rate.

"Because species in natural communities are interconnected, the effects of climate change on any single species can easily be underestimated," said Saran Twombly, program director in the National Science Foundation's Division of Environmental Biology, which funded the research.

"This study combines long-term, data models, and an understanding of species interactions to underscore the complex effects climate change has on natural populations."

"It's very unusual for research to uncover a simple mechanism that can explain almost all the variation in growth rate of an insect population," said David Inouye, a biologist at the University of Maryland and co-author of the paper.

Indeed, "one climate parameter can have multiple effects on an organism's population growth," Boggs said. "This was previously not recognized for species such as butterflies that live for only one year.

"We can already predict that this coming summer will be a difficult one for the butterflies," she said, "because the very low snowpack in the mountains this winter makes it likely that there will be significant frost damage."

"Long-term studies such as ours are important to understanding the 'ecology of place,' and the effects of weather and possible climate change on population numbers," said Inouye.

"This research is critical to assessing the broader effects of weather on an ever-changing Earth," he said. "By facilitating long-term studies, field stations such as the Rocky Mountain Biological Laboratory are an invaluable asset."

Stanford University's Vice Provost for Undergraduate Education also funded the work.

-NSF-

Media Contacts
Cheryl Dybas, NSF, (703) 292-7734, cdybas@nsf.gov

Related Websites
Live Chat: Spring Forward--The Ecological Impact of Climate Change on the Seasons: http://news.sciencemag.org/sciencenow/2012/03/live-chat-spring-forwardthe-ecol.html
NSF News Release: Where Have All the Flowers Gone?: http://www.nsf.gov/news/news_summ.jsp?cntn_id=119843

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2014, its budget is $7.2 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives about 50,000 competitive requests for funding, and makes about 11,500 new funding awards. NSF also awards about $593 million in professional and service contracts yearly.

 Get News Updates by Email 

Useful NSF Web Sites:
NSF Home Page: http://www.nsf.gov
NSF News: http://www.nsf.gov/news/
For the News Media: http://www.nsf.gov/news/newsroom.jsp
Science and Engineering Statistics: http://www.nsf.gov/statistics/
Awards Searches: http://www.nsf.gov/awardsearch/

 

Photo of a researcher catching Mormon Fritillary butterflies in the Rocky Mountains of Colorado.
A researcher catching Mormon Fritillary butterflies in the Rocky Mountains of Colorado.
Credit and Larger Version

Photo of Mormon Fritillary butterflies mating in the Rocky Mountains.
Mormon Fritillary butterflies mating in the Rocky Mountains: will this population survive?
Credit and Larger Version

Photo of frost-killed bud of aspen fleabane daisy.
A frost-killed bud of aspen fleabane daisy; the frost damage means no nectar for butterflies.
Credit and Larger Version

Photo of a Mormon Fritillary caterpillar on violet.
A Mormon Fritillary caterpillar on violet; plants in this genus are eaten by the caterpillars.
Credit and Larger Version

Photo of a Mormon Fritillary caterpillar feeding on a leaf.
Last of the Mormon Fritillary butterflies? Early snowmelt may be to blame.
Credit and Larger Version



Email this pagePrint this page
Back to Top of page