Joel Kontinen
Mutations do not explain why some Mexican cave fish (Astyanax mexicanus) have lost their eyesight.
New Scientist reports on recent research of these fish:
"Aniket Gore of the US’s National Institute of Child Health and Human Development and colleagues haven’t found any disabling changes in the DNA sequences of eye development genes in the cavefish.
Instead, the genes have been switched off by the addition of chemical tags called methyl groups. This is what is known as an epigenetic, rather than genetic, change.”
It would not be honest to call this Darwinian evolution, as it isn't.
New Scientist calls it an unexpected evolutionary process, but it would be more appropriate to call it a non-evolutionary process or a non-Darwinian process.
The fish did change, they lost a feature they had (eyesight), but the cause of their adaptation to darkness is anything but Darwinian.
Source:
Le Page,Michael. 2017. Blind cave fish lost eyes by unexpected evolutionary process. New Scientist (12 October).
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