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The Amazon Molly (Poecilia formosa) lives in SW US and Mexico, not the Amazon. (Mollies are a group of related fish species commonly kept in aquariums.) Its called Amazon that because it is an all female species. It mates with males related species, but does not use any of the male's DNA. Thus, it is a clonal organism. Each new individual only uses the DNA of its single ancestor and neither acquires not losses any sequences from generation to generation.
Based on our normal understanding of things, this would present problems for the species:
1) Bad (deleterious) mutations would accumulate through the generations until the species was producing only genetically enfeebled individuals (non-adaptive). This is called Muller’s ratchet.
2) New gene combinations would now be formed each generation by meiosis as they normally would, reducing the populations total genetic diversity of gene (allele) combinations. This is called the Red Queen hypothesis.
3) Recombination would separate closely linked good (beneficial) and bad (deleterious) alleles so selection could act on them separately (rather than ass a tightly linked unit). No cool name for this one.
These problems imply species like this should be short-lived. The Amazon Molly however is a robust species (large individuals producing many offspring), is long lived (estimated to have gone through about 500,000 generations), has a lot of genetic diversity (genome sequencing).
Here are links to a short popular article (The Scientist) on it and to the open access research article (Nature Ecology and Evolution).
The Amazon Molly though to be the result of a single hybridization event between two distantly related molly species, resulting in very high gene diversity which is frozen due to the clonal nature of its reproduction. This is similar to a previous thread on a hybrid crayfish. Duplicating this event in the lab has not been successful (Mollies are live bearers and are easy to breed).
It is hypothesized that this is due to the hybridization event resulting in a very unlikely combination genetics from each of the parents, allowing it to successfully bypass meiosis (and to live long and prosper).
If you are interested in this stuff, the Nature article is quite interesting and discusses a lot of details and possible reasons this works.
Based on our normal understanding of things, this would present problems for the species:
1) Bad (deleterious) mutations would accumulate through the generations until the species was producing only genetically enfeebled individuals (non-adaptive). This is called Muller’s ratchet.
2) New gene combinations would now be formed each generation by meiosis as they normally would, reducing the populations total genetic diversity of gene (allele) combinations. This is called the Red Queen hypothesis.
3) Recombination would separate closely linked good (beneficial) and bad (deleterious) alleles so selection could act on them separately (rather than ass a tightly linked unit). No cool name for this one.
These problems imply species like this should be short-lived. The Amazon Molly however is a robust species (large individuals producing many offspring), is long lived (estimated to have gone through about 500,000 generations), has a lot of genetic diversity (genome sequencing).
Here are links to a short popular article (The Scientist) on it and to the open access research article (Nature Ecology and Evolution).
The Amazon Molly though to be the result of a single hybridization event between two distantly related molly species, resulting in very high gene diversity which is frozen due to the clonal nature of its reproduction. This is similar to a previous thread on a hybrid crayfish. Duplicating this event in the lab has not been successful (Mollies are live bearers and are easy to breed).
It is hypothesized that this is due to the hybridization event resulting in a very unlikely combination genetics from each of the parents, allowing it to successfully bypass meiosis (and to live long and prosper).
If you are interested in this stuff, the Nature article is quite interesting and discusses a lot of details and possible reasons this works.