I was kind of happy you killed it, I thought I had a way out!
OK, then when the answer to your question is “your basic assumptions are very wrong, and you should consult a simple biology book to gain a fundamental understanding of the concepts”
Then you should probably follow that advice.
Sperm are haploid (single copy), and at any locus (physical position in the genome) they contain only one of the two alleles (versions of a gene) in the father’s diploid (two copy) genome. So sperm may differ from one another at any locus where the father is heterogyzous (has two different alleles).
Sperm can certainly be differentially affected by environmental factors that are relevant to genes that are expressed in the sperm. If (say) the father is a heterozygous carrier of a loss-of-function mutation in a key metabolic gene, then the half of the sperm that get the defective allele will die. If the father is heterozygous for a metabolic gene where the alleles are slightly different, and (say) one allele produces a gene product that functions better at low temperature, then all sperm could function equally well at higher temperatures, but half could be favored at lower temperatures. This is all ordinary natural selection at work.
What is utterly implausible is that sperm could be favored based on differences in DNA sequence* for genes that are not expressed in sperm - and the fact that sperm do not have brains gives a clue about what genes are not expressed. First of all, you would need a mechanism to read the DNA sequence in the sperm in order to even know the difference, and sperm chromatin is packed very tightly to protect it. Let alone the fact that even if there were a mechanism to read the sperm DNA sequence, there is nothing in your body that “knows” what phenotype is encoded by an allele when the gene is not expressed. Natural selection operates by expressing a gene and realizing a phenotype.
(*other than gross differences, like the X/Y chromosome difference)
I was aware of this before I started the topic and almost did not start the topic because of this. I have another dumb question, but I am going to ask it anyway. If we photographed active sperm and somehow computer analyzed the activity of the sperm to where the computer knew what types were doing what. And then we somehow filtered the seminal fluid out and reintroduced fluid from another person with a radically different personality and re photographed the active sperm. If they behaved differently would that mean anything?
What activity? Sperm swim, and we certainly examine their motility - this is a routine part of fertility tests.
But you can’t tell which sperm is going to grow up to be Hitler by looking at its behavior when it’s a sperm.
What if it had a little mustache painted on the front? That would seem to be a clear giveaway.
Okay I’m done
#1 In what sense are you done?
#2 Are you really?
Let me just ask one more question. The question that got me thinking about the first question. Suppose the entire human race was under a lot of stress. The population was dropping at an alarming rate. say 10% per century. Is their any mechanism in nature that will start throwing out a higher rate of mutations looking for something that might work? Besides natural selection.
I was joking, I don’t have anymore questions
Stress-induced mutagenesis is a well known phenomenon in some bacteria and unicellular eukaryotes.
I’m not aware of evidence for anything similar in higher eukaryotes. The huge difference in reproductive generation time is probably important.
In that case, you didn’t need to visit the website. All you needed to do was to do what I did, which was to read the bit of it that was quoted in this thread.
You responded to that quote by saying it was “good info”. Why did you do that, if you knew that it was nonsense?
I can’t play moderator, but I will point out the question was posted in IMHO, not Factual Questions. I thought the board was more lenient about cites with regard to opinions. That said, cites are always good.
How would natural selection know that the population was dropping in order to do this? It’s not sentient.
I am also not a moderator. But I wasn’t asking for cites about opinions; I was asking for cites about information claimed to be factual.
A lot of topics get discussed in IMHO; some of them cites aren’t applicable to, some of them cites do seem to me to be applicable to; or at any rate some posts in such threads seem to me to call for cites.
No matter which way you slice it, this is a weird OP for IMHO.
I scanned over the post and it was addressing the information I was looking for. I assumed you would send a worthwhile post. I just didn’t have time at that moment to check out the site.
It’s the organism that needs to know, not natural selection. An organism would more likely respond to the stressor that is causing increased mortality rather than the population size itself. But it is plausible that a unicellular organism in a colony could respond directly to population size. If all cells in the colony secreted something, the extracellular concentration could depend on colony size.