Mountain marmots made bigger by climate change, says new study

Marmots are waking up earlier from hibernation because of longer summers - <em>News Release</em>

Imperial College London News Release

Under STRICT embargo until:
18.00 BST
Wednesday 21 July 2010

Longer summers are causing large mountain rodents called marmots to grow larger and get better at surviving, according to a 33-year study published today in Nature.

The research, carried out by scientists at Imperial College London and collaborators in the UK and USA, looked at a population of yellow-bellied marmots (Marmota flaviventris), which are large ground-dwelling 'squirrels' that live at around 3000 metres in the Colorado Rocky Mountains.

Regional changes in the climate have created longer summers and have led to marmots waking up earlier from hibernation, giving them more time to reproduce and gain weight before the next hibernation period. The study shows that the marmots are growing fatter and healthier as a result. Longer summers also mean that individual marmots are reproducing earlier and their offspring are more likely to survive the upcoming winter, so the marmot population is increasing in size.

Yellow-bellied marmots are adapted to living in environments with a short summer and a long winter by hibernating for seven to eight months of the year. Failure to gain enough weight before the colder months can be life-threatening, as a marmot loses around 40 percent of its body mass during hibernation.

Today's study, which began in 1962 and focuses on the most comprehensive data collected between 1976 and 2008, is the first study of any species to show that a shift in seasonal timing can cause changes in body mass and population size simultaneously.

Dr Arpat Ozgul, lead author of the study from the Department of Life Sciences at Imperial College London, said: "Marmots are awake for only four to five months of the year. These months are a busy time for them - they have to eat and gain weight, get pregnant, produce offspring and get ready to hibernate again. Since the summers have become longer, marmots have had more time to do all these things and grow before the upcoming winter, so they are more likely to succeed and survive.

"We have observed changes in the body mass of individual marmots over the past 33 years and changes in their population size over the last decade, but we do not know what might happen in the future. Will populations thrive in the changing climate? We suspect that this population increase is a short-term response to the lengthening summers. We hope that by continuing this long-term study we will shed important light on the marmots' future response to climate change," added Dr Ozgul.

To reach their conclusions, the researchers analysed data on body mass, survival and reproduction of female yellow-bellied marmots in the Rocky Mountains in Colorado. Every year, the researchers live-trapped marmots at each colony multiple times during the summer and individually marked them using numbered ear tags. They recorded the sex, mass and reproductive condition of each captured animal.

The results show that the average mass of adult marmots increased from 3094 grams in the first half of the study to 3433 grams in the second half. The research also shows that population growth increased from 0.56 marmots per year between 1976 and 2001 to 14.2 marmots per year between 2001 and 2008.

Professor Tim Coulson, one of the authors of the study from the Department of Life Sciences at Imperial College London, said: "The marmots have provided yet another example of how climate change can impact the natural world. We have shown how we can model the consequences of environmental change on wild populations. If we can get better at predicting how climate change is likely to influence the natural world, perhaps we can devise ways to help species predicted to be adversely affected by our rapidly changing climate."

Professor Sir Brian Hoskins, Director of the Grantham Institute for Climate Change at Imperial College London, said: "Scientists have carried out numerous studies on animals and plants that can tell us about the impacts of climate change. Today's study shows that marmots are also one of these species, acting as climate change 'canaries', giving us an early warning about the effects of climate change on our natural environment."

The research was carried out by scientists from Imperial College London, the University of Sheffield, University of Florida, University of Kansas, University of California, Los Angeles, and Stanford University. It was funded by the Natural Environment Research Council (NERC), the Wellcome Trust, National Science Foundation (NSF), the National Institutes of Health (NIH) and the National Institute of Aging (NIA).

-Ends-

For further information please contact:

Lucy Goodchild
Press Officer
Imperial College London
Email: lucy.goodchild@imperial.ac.uk
Tel: +44(0)20 7594 6702
Out of hours duty press officer: +44(0)7803 886 248

Notes to Editors:

1. "Coupled dynamics of body mass and population growth in response to environmental change" Nature, 21 July 2010
Corresponding author: Dr Arpat Ozgul, Imperial College London
(For full list of authors please see paper)

2. About Imperial College London

Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.

Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainabl e sources of energy and address security challenges.

In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.

Website: www.imperial.ac.uk

3. With nearly 24,000 students from 124 countries, the University of Sheffield is one of the UK's leading and largest universities. A member of the Russell Group, it has a reputation for world-class teaching and research excellence across a wide range of disciplines. The University has won four Queen's Anniversary Prizes (1998, 2000, 2002, 2007). These prestigious awards recognise outstanding contributions by universities and colleges to the United Kingdom's intellectual, economic, cultural and social life. Sheffield also boasts five Nobel Prize winners among former staff and students and many of its alumni have gone on to hold positions of great responsibility and influence around the world. The University has well-established partnerships with a number of universities and major corporations, both in the UK and abroad. Its partnership with Leeds and York Universities in the White Rose Consortium has a combined research power greater than that of either Oxford or Cambridge.
For further information, please visit www.sheffield.ac.uk

4. The Wellcome Trust is a global charity dedicated to achieving extraordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust's breadth of support includes public engagement, education and the application of research to improve health. It is independent of both political and commercial interests. www.wellcome.ac.uk

5. The Natural Environment Research Council (NERC) is the UK's main agency for funding and managing world-class research, training and knowledge exchange in the environmental sciences. It coordinates some of the world's most exciting research projects, tackling major issues such as climate change, environmental influences on human health, the genetic make-up of life on earth, and much more. NERC receives around £400 million a year from the government's science budget, which it uses to fund independent research and training in universities and its own research centres. www.nerc.ac.uk