Are there organisms that are more resistant to mutations than others?

I don’t mean species that are just very well adapted to their niches and don’t face much selection pressure, but species whose DNA or cells are innately more resistant to errors or better at self-repair after damage. Is this something that can vary between species or do DNA mutations occur at a lower level that it affects all of life more or less equally?

Eukaryotes (like us, or oak trees, or amoebas) have some pretty sophisticated DNA repair mechanisms that can repair a lot of mutations. Viruses don’t, so, viruses, if you count them as organisms, are probably a good bit more susceptible to mutations than we are. I do not know for sure, but I think it is quite likely that many prokaryotes, such a bacteria, do not have such sophisticated DNA repair mechanisms as eukaryotes do, so they may be more vulnerable too. On the other hand, I would not rule out the possibility that some prokaryotes might have better repair mechanisms than we do. They are a very large and various group of species. (It may also very well be the case that the efficiency of DNA repair varies between different eukaryotic species.)

Maybe my favorite bacteria,* Deinococcus radiodurans?*

Wouldn’t that be a catch-22?

Evolution works by random mutation, and then selecting the best ones. How would it be possible to evolve a resistance to mutation?

This is biology. Any question that begins “Is there any variation in…” is always going to be answered “YES!!” As a trivial example, take E. coli. It was discovered not all that long ago that when E. coli gets stressed, meaning it’s in an unfavorable environment, it can turn on a “backup” DNA polymerase that has a higher tolerance for mismatches than the normal DNA polymerase does. In essence, it realizes it’s in a bad place, and starts deliberately introducing mutations into its genome every time it divides, hoping that one or more of its daughter cells down the line will happen to get a mutation it needs to survive the harsh environment.

In more complex organisms, I suspect most of the variation you’d find would be in DNA repair mechanisms. We all have various pathways devoted to detecting and fixing mutations. These pathways all involve proteins, and any time proteins are involved, there’s potential for mutation and variation. I once wrote up a proposal for a project in which we would measure various peoples’ capacity for DNA repair, and then map the observed variation to the genome to find out which genetic variations were responsible. It never happened, though.

OK, so DNA polymerase can be more or less faithful at reproducing DNA, and DNA repair mechanisms can be more or less efficient. But what about the DNA itself? Can variation in DNA affect its susceptibility to mutation? Well, there are mutation “hot spots” and “cold spots” - regions of the genome that either mutate a lot more than average or a lot less. We don’t understand them entirely, but it appears likely that these have less to do with DNA sequences and more to do with proteins binding to and protecting the DNA, or else leaving it bare and open to insult from mutagens. So we’re back to proteins.

Personally, I don’t think there’s any reason to suspect innate differences at the DNA level. DNA is DNA is DNA - that’s why we can have bacteria making human insulin for us. However, since this is biology, if we think hard enough, we can always come up with an exception to the rule.

One type of mutation is thymine-thymine dimers. When you have two Ts next to each other in the DNA sequence, a stray UV photon can cause them to bind each other rather than their correct binding partners, and this can be misrepaired into a mutation. So if you had a hypothetical DNA sequence that never had a TT pair, it would be resistant to that particular type of mutation.

Generally, though, I don’t think there’s much difference at a DNA level. At the protein level, absolutely.

Mutation, in evolution, is sort of a NIMBY situation. I’m all for mutations happening, as long as it’s not in MY cells. Let all the other individuals experiment and find the good mutations, and then I’ll just incorporate them into my offspring via sex. But other than that, I want my kids to inherit all of my proven, nicely working genes. So there’s a constant tension between pro-mutation and anti-mutation mechanisms. If we were just pro-mutation all the way, we’d have no DNA repair mechanisms at all.