This article is speculating about evolution of species which is not based on changes in DNA.
Horizontal Gene Transfer
Currently, evolution is seen as DNA-based, because DNA is regarded as the only part of organisms that is inherited. DNA is the blueprint for an organism in the next generation. Richard Dawkins, in his book “The Selfish Gene” even shifted the focus of natural selection from complete genomes (species) to single genes. There is recently some unrest about Horizontal Gene Transfer (HTG, also called Lateral Gene Transfer). HTG is troubling, because it impacts our view of the tree of life. If genes are tranfered from one species to another, then the Tree of Life no longer has only branches (where species split of), but also knots (where the genome of different species are mixed to produce a new species).
Horizontal Gene Transfer is however not the only reason that the Tree of Life might have knots. There are researched cases of new species developed from hybridization of two other species, for example in the butterfly genus Heliconius and cichlids in Lake Tanganyika (fishes in East Africa).
The beneficial prion
A prion is an infectious protein. Some diseases are caused by prions, such as the Mad Cow Disease. A protein is a long chain of amino acids. Proteins can carry out their function in a cell because they have a special three-dimensional shape. Some proteins can be folded in different shapes. When such a protein has been folded differently, it will no longer be able to carry out the function it used to do. Prions are proteins that are shaped differently and also have the ability to refold other proteins into their own shape. The latter makes prions infectious. Once a single prion comes into a cell, it folds another protein. After finishing the job, there are two differently shaped proteins which each can fold another protein into their own shape. Then there are four, eight, sixteen etc of them.
It is interesting to notice that prions are self replicators. They require a very specific substrate which is only found in certain living cells.
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