Thursday, March 2, 2017

The Woolly Mammoth's Last Stand

In a remote island off of Siberia, geneticist discovered the tooth of a male woolly mammoth which decodes the probable cause of the population's extinction. This revelation supports the idea that as a population dwindles, natural selection becomes less efficient at deleting bad mutations, and leads to a loss of genes and slowly meltdown the genome. Once numbers fall below a certain level, genetic decline is irreversible and the species will go extinct. The first woolly mammoth's to go extinct were from the mainland due to climate change and hunting, but other populations lived on for thousands of years on remote islands (St. Paul and Wrangel). 
The genomes of the 45,000 year extinct mainland mammoth and the 4,300 extinct Wrangel mammoth were analyzed and geneticist were also able to identify the population size. The population size of the Wrangel was 300 and the mainland had 13000. During the period in between the extinction of both mammoth populations, the species size decreased tremendously and the genetic diversity reduced by 20 percent. This means the lesser fit of the Wrangel mammoths contributed to the extinction.
The Wrangel mammoth's genome detected many deleterious genes and mutations which lead to the population to a genetic meltdown. Many of these genes halted the synthesis of proteins, and damaged olfactory genes as well as receptors which detect pheromones, The two snapshots of the woolly mammoth genome, support the idea that there is genomic meltdown in small populations which contributes to extinction.The discovery that individual genes were deleted in the Wrangel mammoth’s genome is a “very novel result,” and if confirmed, “will have very important implications for conservation biology,” Dr. Dalen said.

I found this article very interesting in many ways. Genetic technologies have become so advanced in analyzing genomes, that the tools can get results from hundreds of thousands of years ago. I also always believed the woolly mammoth's extinction resulted from climate changes, but never thought of mutations being the cause. The mutations found on the genome of the Wrangel mammoth proved to be the final blow to the extinction of the species. The mammoth's were unable to use special senses for survival as well as not being able to socialize with the other sex due to damaged receptors of pheromones. It seems that over time, the mutations weeded out vital genes until there was nothing left to salvage.The mutations were the ultimate destruction of the mammoth species and is important information for conserving endangered species today. 

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