Global warming affects warm-weather
species too, study finds
From : Mr. Phill Hamton
Even tropical plant and animal species living in some of the warmest places on Earth may
face threats from a warming planet, according to new research co-authored by a UCLA
scientist.
Evolutionary biologist Alex Gilman and her colleagues collected data on the altitudinal
ranges of nearly 2,000 plant and insect species living on the forested slopes of a Costa
Rican volcano that rises some 10,000 feet. They found that about half the species have
such narrow altitudinal ranges that a 2,000-foot uphill shift caused by warming
temperatures would move them beyond the upper limits of their current ranges. Their
research appears Oct. 10 in Science magazine.
The researchers also found that many species may be unable to shift because
mountainside forests in the tropics have been severely fragmented by human land use.
Meanwhile, tropical lowland rainforests, the warmest forests on Earth, face a challenge
that has no parallel at higher latitudes. If the current occupants of the lowlands shift
uphill, tracking their accustomed climate, there are few potential replacements currently
living in even warmer places. According to Gilman and her colleagues, the threat of
lowland attrition from warming climates could affect about half the species they studied
in Costa Rica unless lowland species retain tolerances to higher temperatures developed
millions of years ago when the world was much warmer.
"Our research suggests that the effect of global climate change on some tropical
rainforest and mountain species could be significant," said Gilman, who earned
her doctorate from the UCLA Department of Ecology and Evolutionary Biology while
conducting the research. "Only additional research can estimate the risk."
Philip Rundel, UCLA distinguished professor of ecology and evolutionary biology,
supervised Gilman's work.
"While the effects of climate change of certain species have been well-documented," he
said, "there has been surprisingly little attention given to the effects of a warming climate
on tropical plants and animals."
The lead author of the Science magazine study was Robert Colwell, of the University of
Connecticut.
As the Earth's climate has warmed in recent decades, the geographical ranges of wellstudied bird, butterfly and plant species in the U.S. and Europe have moved northward,
following the gradual northward shift of their familiar climates. Other studies have shown
that species in the U.S. and Europe have shifted to higher elevations, as temperature
zones on mountains have moved upward.
The Science study notes that tropical climates have warmed more than 1.4 degrees
Fahrenheit since 1975, and climate models predict an additional increase of nearly 6
degrees over the next century in the tropical forests of Central and South America.
Such warming would shift temperature zones uphill about 2,000 feet. Tropical species,
like those at higher latitudes, will likely be driven to higher elevations by these changes,
following the climate zones for which they are suited, according to the study.
UCLA is California's largest university, with an enrollment of nearly 38,000
undergraduate and graduate students. The UCLA College of Letters and Science and the
university's 11 professional schools feature renowned faculty and offer more than 323
degree programs and majors. UCLA is a national and international leader in the breadth
and quality of its academic, research, health care, cultural, continuing education and
athletic programs. Four alumni and five faculty have been awarded the Nobel Prize. For
more news, visit the UCLA Newsroom.
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Media Contacts
Phil Hampton,
310-206-1460
phampton@support.ucla.edu