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It's like this: now that full-genome sequencing is getting pretty cheap and common, you can tell how string the selection pressure is on a chunk of DNA just by

It's like this: now that full-genome sequencing is getting pretty cheap and common, you can tell how string the selection pressure is on a chunk of DNA just by looking at frequencies of variants. If it turns out there are very few variants, you can be confident the chunk is doing something, even if you don't know what. If the variation looks like random drift, you can be pretty confident it is.

moralestapia 2y ago
No, you seem to only have a casual/superficial understanding of the field. There's an abysmal number of post-transcriptional effects that are functional. Start with something like [1]. There's also plenty of evidence (like TFA and [2]) of "junk" DNA turning out to be functional through some contrived and completely unexpected mechanisms. Every time someone says something like "this is how Biology works" one can lmao all the way to the lab. 1: https://en.wikipedia.org/wiki/Epigenetics https://en.wikipedia.org/wiki/Epigenetics 2: https://pubmed.ncbi.nlm.nih.gov/36484387/ https://pubmed.ncbi.nlm.nih.gov/36484387/
- _qua 2y ago
  As others and I have mentioned above, there are absolutely parts of the genome that are functional despite being non-coding. There is no debate about this. You have shared links and arguments emphasizing that there is function in these parts. However, you have not addressed the fact that there are large stretches of DNA that are not conserved across species, show no differential selection pressure compared to what would be expected from random genetic drift, and that there are hugely varying sizes of genome between species. From my reference below: "If most eukaryotic DNA is functional at the organism level, be it for gene regulation, protection against mutations, maintenance of chromosome structure, or any other such role, then why does an onion require five times more of it than a human?" Of course, one can always say, "How arrogant to think we know everything." But given our current understanding of evolution and genetic function, the specific identity of a genetic sequence correlates with its function. If that function is important, the sequence should be preserved to a degree better than random chance. To deny this is to suggest that any random sequence of genetic material can serve a vital purpose while being subject to endless mutation without consequence. This raises the question: What do we mean by a "specific sequence" if it isn’t conserved and is constantly mutating? I assume you are familiar with the information I’ve just shared. I’m curious where we are diverging in our views because it feels like we are not discussing the same thing. This artcle fairly represents my understanding of what I mean when I say "junk DNA": https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351 https://journals.plos.org/plosgenetics/article?id=10.1371/jo...

moralestapia 2y ago

No, you seem to only have a casual/superficial understanding of the field. There's an abysmal number of post-transcriptional effects that are functional. Start with something like [1]. There's also plenty of evidence (like TFA and [2]) of "junk" DNA turning out to be functional through some contrived and completely unexpected mechanisms. Every time someone says something like "this is how Biology works" one can lmao all the way to the lab. 1: https://en.wikipedia.org/wiki/Epigenetics https://en.wikipedia.org/wiki/Epigenetics 2: https://pubmed.ncbi.nlm.nih.gov/36484387/ https://pubmed.ncbi.nlm.nih.gov/36484387/

_qua 2y ago
As others and I have mentioned above, there are absolutely parts of the genome that are functional despite being non-coding. There is no debate about this. You have shared links and arguments emphasizing that there is function in these parts. However, you have not addressed the fact that there are large stretches of DNA that are not conserved across species, show no differential selection pressure compared to what would be expected from random genetic drift, and that there are hugely varying sizes of genome between species. From my reference below: "If most eukaryotic DNA is functional at the organism level, be it for gene regulation, protection against mutations, maintenance of chromosome structure, or any other such role, then why does an onion require five times more of it than a human?" Of course, one can always say, "How arrogant to think we know everything." But given our current understanding of evolution and genetic function, the specific identity of a genetic sequence correlates with its function. If that function is important, the sequence should be preserved to a degree better than random chance. To deny this is to suggest that any random sequence of genetic material can serve a vital purpose while being subject to endless mutation without consequence. This raises the question: What do we mean by a "specific sequence" if it isn’t conserved and is constantly mutating? I assume you are familiar with the information I’ve just shared. I’m curious where we are diverging in our views because it feels like we are not discussing the same thing. This artcle fairly represents my understanding of what I mean when I say "junk DNA": https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1004351 https://journals.plos.org/plosgenetics/article?id=10.1371/jo...