We’ve found out why a Mexican cavefish has no eyes – and the surprising answer is likely to be seized upon by those who think the standard view of evolution needs revising.
Over the past few million years, blind forms of the Mexican tetra (Astyanax mexicanus) have evolved in caves. Maintaining eyes and the visual parts of the brain uses lots of energy, so the loss of eyes is a big advantage for animals living in the dark. Instead the cavefish “see” by sucking.
It was assumed that these fish became blind because mutations disabled key genes involved in eye development. This has been shown to be the case for some other underground species that have lost their eyes.
But 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.
Did blind cavefish evolve by breaking the laws of evolution?
BettSplendens Tumblr Evac 