Insect Population Growth Likely Accelerated By Warmer Climate

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Insect Population Growth Likely Accelerated By Warmer Climate
http://www.terradaily.com/reports/Insect_Population_Growth_Likely_Accelerated_By_Warmer_Climate_999.html

by Staff Writers
Seattle WA (SPX) Oct 31, 2006

Insects have proven to be highly adaptable organisms, able through evolution to cope with a variety of environmental changes, including relatively recent changes in the world's climate.

But like something out of a scary Halloween tale, new University of Washington research suggests insects' ability to adapt to warmer temperatures carries an unexpected consequence - more insects.

It appears that insect species that adapt to warmer climates also will increase their maximum rates of population growth, which UW researchers say is likely to have widespread affects on agriculture, public health and conservation.


Many studies have shown that insects readily adapt to the temperature of their environment. For example, those living in deserts easily tolerate high temperatures but are much less tolerant of cold temperatures than insects living in mountains. Now UW biology researchers have found that insect species that have adapted to warmer environments also have faster population growth rates. The research shows, in effect, that "warmer is better" for insects, said Melanie Frazier, a UW biology doctoral student.


"Enhanced population growth rates for butterflies might be a good thing, but enhanced growth rates for mosquito populations is much more dubious," said Frazier, who is lead author of the new research, published in the October edition of the journal The American Naturalist.


Co-authors are Raymond Huey, a UW biology professor, and David Berrigan, a former UW biology researcher now with the National Cancer Institute.


The findings suggest that evolutionary adaptation to climate warming will have profound ecological effects because rates of population growth eventually will alter entire ecosystems, Frazier said. In addition, key ecosystem characteristics such as species diversity and food webs are very sensitive to the population growth rates of the species living and interacting in those ecosystems.


She noted that biochemical adaptation to warmer temperature is not the only possible insect response to climate warming. Some species might evade warmer temperatures by moving to cooler habitats, or they might alter their seasonal activity patterns. Others might not be able to adapt adequately and could become extinct. But those that do adapt should have elevated rates of population growth.


"No matter which scenario plays out for a given species, local ecosystems will be profoundly altered," Frazier said.



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[Snowy Owl]

Re: Insect Population Growth Likely Accelerated By Warmer Climate

The Power Behind Insect Flight: Researchers Reveal Key Kinetic Component
http://www.terradaily.com/reports/The_Power_Behind_Insect_Flight_Researchers_Reveal_Key_Kinetic_Component_999.html
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by Staff Writers
Troy NY (SPX) Oct 31, 2006

Researchers from Rensselaer Polytechnic Institute and the University of Vermont have discovered a key molecular mechanism that allows tiny flies and other "no-see-ums" to whirl their wings at a dizzying rate of up to 1,000 times per second. The findings are being reported in the Oct. 30-Nov. 3 online early edition of the Proceedings of the National Academy of Sciences (PNAS).

"We have determined important details of the biochemical reaction by which the fastest known muscle type -- insect flight muscle -- powers flight," said Douglas Swank, assistant professor of biology at Rensselaer and lead author of the PNAS paper.


The findings will help scientists gain a better understanding of how chemical energy is converted into muscle movements, such as human heart muscle pumping blood. The research also could lead to novel insights into heart disease, and might ultimately serve in the development of gene therapies targeted toward correcting mutations in proteins that detrimentally alter the speed at which heart muscle fibers contract.


Since insects have been remarkably successful in adapting to a great range of physical and biological environments, in large part due to their ability to fly, the research also will interest scientists studying the evolution of flight, Swank noted. The project is supported by a three-year $240,000 grant from the National Institutes of Health and a four-year $260,000 grant from the American Heart Association.


The research is focused on a key component of muscle called myosin, the protein that powers muscle cell contraction. Swank's team focused its efforts on the fruit fly and asked a basic question: Why are fast muscles fast and slow ones slow? The researchers discovered that the reaction mechanism in insect flight muscle on the molecular level is different from how slower muscle types work.


"Most research has focused on slower muscle fibers in larger animals," Swank said. "By investigating extreme examples, e.g. the fastest known muscle type, the mechanisms that differentiate fast and slow muscle fiber types are more readily apparent."


In general, myosin breaks down adenosine triphosphate (ATP), the chemical fuel consumed by muscles, and converts it into force and motion. To do this, myosin splits ATP into two compounds, adenine diphosphate (ADP) and phosphate. Each compound is released from myosin at different rates.
In slow-muscle contraction, ADP release is the slowest step of the reaction, but in the fastest muscle fibers, Swank's team has discovered that phosphate release is the slowest step of the reaction.


This finding is significant because the overall chemical reaction rate is set by the slowest step of the reaction. "What we have found is that in the fastest muscle type, ADP release has been sped up to the point where phosphate release is the primary rate-limiting step that determines how fast a muscle can contract," Swank said.


The next step, according to the researchers, is to experiment with other fast muscle types, such as the rattlesnake shaker muscle and fast mammalian muscle fibers. "By broadening our research, we will be able to determine if the phosphate release rate contributes to setting muscle speed in fast muscle types from other species," according to Swank.


Swank's collaborators on the project are Vivek K. Vishnudas and David W. Maughan of the Department of Molecular Physiology and Biophysics at the University of Vermont.



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Rensselaer Polytechnic Institute