Chernobyl black frogs reveal evolution in action
phys.org
phys.org
And does that mean darker-skinned human beings are better suited for space travel?
Whiter skin evolved when humans migrated from Africa to regions with less sun, in order to get more vitamin D.
Planet was colder, and around equator you actually have quite habitable places even now, deserts are further from equator. But you get tons of light whole year in very stable pattern.
We had fur at one point, and our still-furred cousins have pink skin, so our ancestors probably did as well.
It's generally believed to be the case that dark skin evolved with hairlessness, and was lost by some branches of the tree during the glacial period.
Here's a popular-press citation for the consensus that our furred common ancestor was pink skinned: https://www.discovermagazine.com/planet-earth/why-did-darker...
The key points are both dark and pale skin are evolutionary traits once we lost hair. If you sweat you probably want light skin under fur.
Vs.
Human "color" is, at most, skin deep.
Melanin throughout the body could perhaps help protect a little against some ingested radioactive substances (given the mechanisms listed).
However I am guessing the the existing genetic variation was for skin colour, so only the skin colour was likely to be selected for (given the small number of generations).
https://onlinelibrary.wiley.com/doi/10.1111/eva.13476
No genetics were done. Measurements of a sample of 189 only.
(1) This is adaptation, not evolution, but it may be merely selection of a pre-existing color variant that already widely found in nature. We have the same exact variation of melanistic toads & frogs found in the US.
(2) They really don't know how many generations this occurred over, they have a measurement, and a measurement.
(3) The baseline wasn't built before the Cherynobyl event. As a person that has caught a great number of frogs and toads, their coloration in normal areas varies greatly based on the local Flora and sun conditions. The very dark / black frogs which are already found in nature, may have just reproduced better, instead of coloring adaptation being introduced. Frogs that live near asphalt and post-wildfire conditions would be expected to have better survival characteristics due to decreased visibility.
If this variant is being selected for preferentially, that's evolution: "Typically, we think of biological evolution as changes in gene frequency within a population over time – if, say, birds with genes that produce wide beaks went from being rare to being common over multiple generations."
https://evolution.berkeley.edu/evolution-101/mechanisms-the-...
It is a population that evolves, not an individual.
Selection of a pre-existing feature that already occurs in the gene pool is exactly how evolution works. There are only two things needed for evolution: 1) generation of diversity between individuals (see sexual recombination, V(D)J recombination, etc) 2) selection of traits
The fact that black frogs already existed at some frequency does not mean that the population did not evolve in response to radiation.
But you are right that radiation is not the only thing that might select for dark frogs.
Also, there is not single gene for melanin. Several genes are required for the ultimate effect that you observe as dark skin. A mutation in any of these genes, or in any of the transcription factors which control expression of these genes, could lead to observed differences in frog skin color.
FYI, "new genes" are usually the result of duplication of an existing gene (https://en.wikipedia.org/wiki/Gene_duplication#Mechanisms_of...). Duplicating a gene can be useful in and of itself by providing functional redundancy. However, the new copy is then also subject to its own mutations without affecting the original copy, and over time the two genes may diverge in function.
I feel like I hear this a lot - I wonder if our hypotheses about the "natural" speed of evolution are wrong.
There's so much to unpack in that sentence! :)
In general, a layman's understanding of a complex scientific topic is going to be wrong but if we restrict "our hypotheses" to evolutionary biologists, then no. Between the (very popular) equilibrium hypothesis that a sibling linked to, microbiology, and the textbook cases of evolution during the industrial revolution [1], biologists have known for a long time that natural selection can be fast or slow.
Regarding "natural" and tying back into the equilibrium hypothesis: non-cyclical rapid changes to the environment used to be much rarer before humans began building civilization, so pre-historic evolution might have looked significantly different. Nowadays, all it takes is a single ship to accidentally transport an invasive species that will wipe out an ecosystem and leave only the ones best adapted to the new reality.
Last but not least, the "speed" of evolution is actually a combination of two orthogonal factors: the mutation rate and selection pressure. Natural selection can only select from the species that exist (i.e. the ones already surviving) so mutation rate is really what most people mean when they say "speed of evolution". Chernobyl is a very special case where the radioactive fallout increases the mutation rate, reduces lifespans by an average of 30% (IIRC) putting more pressure on survival to sexual maturity, and removes much of human interference from the picture. I wouldn't draw many conclusions on evolutionary biology from Chernobyl unless we plan on turning the entire planet into a fallout zone.
Fruit flies in a jar iterate fast enough if you want to try playing god for a while.
I encourage people to not visit them.
Like going to do pagerank with consent cookies, filter anything with a consent cookie, and anything that links to anything with a consent cookie, see what's left.
Practically I'm not really sure what this does in terms of actual tracking but personally it's the dialog that annoys me more.
I care for my privacy, but the pressure of spyware is everywhere, at multiple levels, and the effort required to counter it completely is excessively asymmetrical.
I don't understand "Why pick the former when the latter works."
No one is picking anything, it's all happening simultaneously. An epigenetic solution would reduce selective pressure for a genetic solution, theoretically.
Maybe the black frogs are at higher risk of melanoma. Nothing is ever free..
(checks page history, nope it's been around a while, I guess you didn't just write it to win this one)
Good catch anyway!
Darwinism, conversely, is about selection from within a range of traits already present (i.e. beak size).
These frogs come in a variety of colors. Dark colors have a better fitness for the highly radioactive environment. Those are the ones that reproduce. This is textbook Darwinian evolution.