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Wednesday, February 8, 2012

Mouse Need 24 Million Generation To Be Elephant

For the first time that scientists have measured how quickly large-scale evolution can occur in mammals. Their results showed, it takes time for 24 million generations for the animal about the size of mice to develop into an elephant.

A study published in the journal Proceedings of the National Academy of Sciences explains the increase and decrease in size of mammals after the extinction of dinosaurs 65 million years ago. The study, led by Alistair Evans of Monash University that involved 20 biologists and paleontologists.

They found that the rate of decline in body size in mammals is much faster than its growth rate. It took only 100 thousand generations for a very large reduction results in dwarfism.

Evans says the study is unique because previously only focused on microevolution, the small changes that occur within a species, rather than large-scale changes in animal body size.
Large evolutionary changes in body size take a very long time. A mouse-to-elephant size change would take at least 24 million generations based on the maximum speed of evolution in the fossil record, according to the work of Alistair Evans and co-authors. Becoming smaller can happen much faster than becoming bigger: the evolution of pygmy elephants took 10 times fewer generations than the equivalent sheep-to-elephant size change. (Picture from: http://www.eurekalert.org/)
"Changes in the size of the 'mouse to elephant' is a big change, but also take a very long time. A less dramatic change is the change of the size of the rabbit to the size of an elephant that takes time for 10 million generations," said evolutionary biologist this.

The team tested 28 groups of mammals, including elephants, primates, and whales, from different continents over the last 70 million years. Change the size of the note in the scale of generations to allow more precise comparisons between different species and life span.

Senior curator of vertebrate paleontology of the Museum Victoria, Erich Fitzgerald, said the whale-sized level changes occur two times faster than land mammals. "This is probably because it's easier to make it big in the water because the water supports the weight," he said.

According to Evans, small animals, such as the pygmy mammoth, pygmy hippos, and hominid "hobbits" who live on islands, could help to explain the particulars of species body size reduction. "When the body is smaller, you would need less food. It's a real advantage if you live in small islands," he said. *** [MONASH UNIVERSITY | MAHARDIKA SATRIA HADI | KORAN TEMPO 3785]Enhanced by Zemanta
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