I was just listening to eons in my car and specifically the episode about armored fish, and the thought occurred to me: isn't evolution ultimately selecting for adaptability?
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It would seem the design that can survive the most extinctions would be the clear winner in the end.
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This makes me wonder, why are there no 100% albino species considering albinos can be found in every species and can only produce other albino offspring when paired with other albinos?
Aren't there, in blind cave species where there's no pressure to select for coloring to protect from the sun or to camouflage or display for mates?
If they can only albino offspring when paired with other albinos that indicates it’s a recessive gene.
Recessive genes don’t take over gene pools unless they confer some survival advantage.
And usually albinos are at a distinct disadvantage. Their camouflage doesn't work, or their mating colors aren't present, or they get burned up by the sun, or a hundred other disadvantages depending on the species and environment.
They get eaten
How does being albino automatically mean being eaten (assuming we rule out species that need camouflage)?
First, the vast majority of species depend on camouflage at least somewhat, since there are very few species that are neither predator nor prey. Also, albinism prevents your skin from properly protecting you from the sun. So even then, it is selected against. As other have pointed out though, caves don’t have either of these forces at play—the darkness makes visual camouflage irrelevant and there is no UV light. So there, as you predicted, most species are albino.
Albino is only used as a term when it's a deviation from the species norm usually. There are all white cave bugs.
I thought albinism had an objective basis in the genetic code.