Have you ever wondered how cave-dwelling species develop unique traits like losing eyes or clear skin? 🤔
#Evolution #CaveDwellingSpecies #UniqueTraits #Adaptation
Exploring the Mystery of Cave-Dwelling Species
How do these fascinating creatures evolve?
– Adaptations to dark environments
– Genetic mutations leading to loss of eyesight
– Clear skin for absorbing nutrients
Similarities among diverse species
– Convergent evolution in caves
– Selection pressures driving unique traits
The role of natural selection
– Survival of the fittest in extreme environments
– Evolutionary advantages of losing eyes or developing transparent skin
Curious to delve deeper into this intriguing topic? Let’s uncover the secrets behind the evolution of cave-dwelling species together! 🦇🔍 #ExploreCaveEvolution #MysteryOfAdaptation
Let’s take simple Mendelian genetics (big A little a stuff) and say that if you have the big A trait you will be 0.1% more efficient in a given environment then the other trait. In only a few hundred generations you will stop seeing the little a trait altogether(assuming it’s recessive). This is because small benefits are still benefits and just by chance will do better till they eclipse the population.
Now another question which you didn’t ask but still relates is how do all these species have similar traits? You may have heard about convergent evolution but recent sciences is actually pretty skeptical of this idea. Basically, there are genetic mechanisms for all sorts of processes which are turned off in a organism. These processes can be easily turned on, leading to a massive jump in a population. This means sometimes these evolutionary changes are very very fast(evolutionary fast so still millions of years). For example, eyes. Vertebrates and cephalopods evolved eyes separately but still use many of the same genetic processes to see which originated in a common ancestor. I really can’t do a great job explaining this in a short format but if you would like to learn more, just let me know!
This is an illustration of how difficult is to be a living thing.
We, as living things, are perpetually showered with radiation. We get energy by slowly burning tiny fires inside our cells, and our own cells spew out toxins. Our food is filled with poisons. Our DNA is constantly under attack from all these destructive forces, and it’s only because of constant frantic effort from the repair machinery that we don’t immediately collapse into greasy puddles of goo.
Every new person (or crab, or redwood tree, or cave lizard) is born with dozens of new mutations. If we’re lucky, none of those mutations damage something important, let alone essential. If we’re not lucky, we’re born without some essential gene, and we don’t survive. Or we’re born without something important, and we may survive but our progeny don’t, and the impersonal logic of evolution trims off our branch with no descendants.
This is negative selection. It’s not positively selecting for an improvement, it’s selecting *against* defects.
OK, so what happens when a gene that was essential, suddenly stops being important? Say the vitamin C pathway, which you absolutely must have unless you’re a primate living on food that is naturally high in vitamin C. Or say you’re a cave fish, living in a place where vision is no use to you.
Now the constant shower of mutations that hit those formerly-essential genes don’t have any negative effects. It doesn’t matter if your vitamin C pathway doesn’t work any more, so there’s no more negative selection, and the mutations are not removed by evolution. Your progeny will be just as healthy as their neighbors who don’t have any mutations.
So those mutations can just randomly drift through the population. You don’t need any positive selection, there doesn’t need to be an advantage to having the mutations; it’s simply that there’s no *disadvantage* any more.
It’s possible there is some positive selection, whether very weak due to saving energy or stronger due to some side effect. But there doesn’t need to be. Harmless, useless mutations can spread through a population perfectly well simply through drift.
(There are whole fields of math that describe how and why this works, but we don’t need to invoke them at all. The concept is pretty simple.)
It doesn’t go from “eyed” to “eyeless” over a single generation. Gradually, over thousands of generations, the eyes would have become less functional until eventually becoming vestigial. This could be because of a positive selection effect e.g. it allows the animal to develop keener hearing instead, or just because having poor eyesight is no longer a disadvantage the way it is for surface-dwelling animals.
Your premise is slightly off. Evolution doesn’t actually care about “advantageous.” Those kind of traits definitely end up presenting, because they do provide an advantage, but the only thing evolution cares about is what traits led to offspring.
That’s the “boiled down” reality of it. There’s arguably more nuance, but honestly not by much.
Why specific traits are more likely than others kinda needs educated guesswork.
Maybe somewhere in the organism’s history, there was a shortage of food (Adversity begets ingenuity). Being in a cave, with no light, the random occurrences of no eyes and no skin pigment suddenly means they are better suited to the situation, and are the ones that get to mate.
So, it’s not so much that they “lost traits to adapt” it’s more that “traits they lost became adaptation.”
There’s a non-zero chance that their ancestors didn’t spend the entirety of their existence in caves. But, because of the situation where “cave specific traits” became so prevalent, they further increased their time in those environments.
Probably something like spending the daylight hours in a cave, and leaving at night (technically don’t need eyes or skin pigments at night). There’s probably a split somewhere where some of their ancestors became 100% cave dwelling, and another branch either died out trying to “have it both ways” or further changed to something else.
A lot of times, when we’re thinking about evolution, we fall into this trap that there’s “some level of intelligent design” behind it. Regardless of your stance on how things started, it’s the opposite, mostly.
Dumb luck, pretty much, that’s the short of it.