This is the blog for GW students taking Human Evolutionary Genetics. This site is for posting interesting tidbits on: the patterns and processes of human genetic variation;human origins and migration; molecular adaptations to environment, lifestyle and disease; ancient and forensic DNA analyses; and genealogical reconstructions.

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Tuesday, February 13, 2018

Under the Sea: Clonal Polymorphism and Heterozygosity in Amazon Molly



In a recent nature article the paradox of the asexual  Amazon Molly, a species of fish that is most commonly found in the Gulf of Mexico, is discussed. The Amazon Molly is unique because it is one of few vertebras that partake in asexual reproduction, more specifically it reproduces through what is known as gynogenesis which means females need a male to mate, however the genetic material from the male is not incorporated in the diploid egg cells provided by the mother, which leads to the subsequent cloning of the mother. Additionally, this species does not conform to the Muller’s Ratchet hypothesis which argues that meiosis is needed in order to purge any bad mutations that could lead to genomic decay, thus making the clonal vertebrae population evolutionarily short lived  and unable to survive after  a certain amount of generations. However, the Amazon Molly exceeds this threshold argued by Muller’s Ratchet  in that is has been phylogentically shown to be at least 100,000 years old and have had about 500,000 generations. So, why has this species survived this long and why aren’t there more vertebrae species that can reproduce asexually? Well, the answer is in the genes! After examining the genome, it has been determined that the rarity of this paradox is not due to it’s inferiority to sexual species, but because the genomic variations which lead to successful survivorship and reproduction of the species is very specific!

You can find the recently published article in nature here
-Sam Lubrano

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