As the climate keeps changing, some species may have one last chance to adapt.
Media Release, Friday 21 December 2007
In a paper released today, scientists reveal that certain fly species can adapt once to climate change, but if the environment changes again, their survival rate plummets.
Researchers from the Universities of Melbourne, Australia and Aarhus, Denmark have been sending flies back and forth for the last three years to determine how they fare in hotter or colder conditions.
As climatic conditions around the globe change rapidly, the distribution of many animal species is expected to be altered as a direct or indirect response to thermal conditions.
Researchers cold-treated adult and young (developing) Drosophila flies- otherwise known as the vinegar fly- in the laboratory in order to fast-track their adaptation to a colder climate. The flies were then released into the field in order to assess survival rates in the hot Australian and cold Danish climates.
Both the developing and adult cold acclimation had enormous benefits at low temperatures in the field; in the coldest releases only cold-acclimated flies were able to find a food resource.
But this adaptation came at a huge cost, when the cold-treated and untreated flies were put into mild or hot conditions, the flies that had not been cold-acclimated were up to 36 times more likely to find a food resource than the cold-acclimated flies. The reverse applied as well – hot adapted flies did poorly in cool conditions.
“One way animals can counter the effects of climatic extremes is via physiological acclimation, but acclimating to one extreme decreases performance under different conditions,” said Professor Ary Hoffmann, Centre for Environmental Stress and Adaptation Research (CESAR) at the University of Melbourne.
“We tested how physiological adaptation through cold acclimation changes the individuals’ ability to perform in a situation where many external stimuli such as humidity, predators, or competitors are present in addition to thermal stimuli.”
“Such costs and strong benefits were not evident in laboratory tests where we found no reduction in heat survival of the cold-acclimated flies. Field release studies, therefore, reveal huge costs of cold and hot acclimation”
“If temperatures fluctuate, organisms acclimated to cold or hot conditions can suffer a decrease in fitness as temperatures move to the middle or the opposite extreme.”
“Species therefore have problems coping with fluctuating environments, an important problem at a time when climatic conditions are becoming more variable”.
“It is therefore important to evaluate cost and benefits of acclimation and other
responses under field conditions by using assays relevant to field performance. Our next step is to perform further field trials with a greater variety of species”.
Pictures available
For further information please contact:
Professor Ary Hoffmann
Tel: 8344 2282
Mob: 0408 342 834
ary@unimelb.edu.au
Media enquiries:
Dr Nerissa Hannink
Media Officer
Tel: 03 8344 8151
Mob: 0430 588 055
nhannink@unimelb.edu.au
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