Archive for evolutionary biology

A Frog’s Evolutionary Tale

Posted in Science with tags , , , , , , , , , on August 10, 2010 by neandergal

Geologists are able to tell the timeline and sequence of tectonic plate movement by studying the genetics of a variety of 24 species of the Paini frog in Asia. Genetic analyses of the frogs allow scientists to determine their evolutionary trail along the Himalayas and Tibetan Plateau.

Formation of mountain ranges caused by movement of the Indian tectonic plate and climate change isolated populations of frogs. The different environments caused by geological changes led to different evolutionary changes in the frogs. From the genetic studies of the different frogs, it appears that the beginning of the mountain ranges of the Himalayas started in the Oligocene period some 34-23m years ago. Species divergences occurred in the Miocene period 5-23m years ago.

Scientists at University California Berkeley and Kunming in China analyzed the species of spiny frog that evolved muscular limbs to hold on tight to their mates in an amphibian grip known as the “Amplexus” (Latin for embrace) and rocks in the fast flowing rivers of their high altitude environment.

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A Lousy Sense of Smell

Posted in Science with tags , , , , , , , , on June 24, 2010 by neandergal

Scientists have mapped the genome of the body louse (Pediculus humanus humanus) and found that it has a lousy sense of smell.

The louse contains 108 million DNA base pairs (bp) whereas their human host genome has three billion bp.The blood of their human host is the exclusive diet of the louse so they did not evolve to have a sense of smell. The louse is responsible for the spread of diseases like typhus and trench fever.

Scientists are itching to learn more about the genome of the louse as it may help to prevent epidemic outbreaks of these diseases among people who live in insanitary conditions.Analysis of DNA reveals that the body louse evolved from head lice when humans started wearing clothes some 190.000 years ago.The evolutionary process of louse will undoubtedly have entomologists scratching their heads for quite some time.

Source: Scientific American: Full genome sequence shows body lice have lousy sense of smell