Selfish Gene Theory

[pineapplebunnybounce]

Hm, ok I see what you're struggling with. I won't be responding parts by parts because I think I may be able to explain it with more context in another order.

First mistake is that genes are not sets of DNA. A set of DNA is made up of multiple genes. So in sexual selection, genes still get passed on, entire ones, they don't split up and only pass on 50%. The benefit of sexual selection is diversity. The potato famine happened because all of the potatoes had the same DNA makeup and all got infected (or what do you call it). That wouldn't have happened if they did not propagate through cloning (exact replicates as offsprings). So if a huge bunch of machines can die, the genes within them get reduced chances of being copied pass this generation.

So in the analogy of the chromosome representing a book, the genes representing the chapters, and the DNA representing the text, you're saying that the chromosome contains all the genes ("chapters") of the male, not 50%, yes? That makes sense (if I'm right)...

Uhmmmm .... What do you mean? XD.

I see now that I wasn't very careful with my terminology. Ok, so we have sets of genes in chromosomes. And DNA is basically the ATGC that make up chromosomes. And genes are ... chapters or words. I prefer words. But doesn't matter, same idea.

So you can split the book without splitting the chapters. Some genes will be cast off during sexual selection, in the form of sperms that did not get there first and in females, it just separates from the egg before ovulation and dies off.

When I said genes still call the shots, I meant a lot of what you do, in fact maybe even all of it, you're only able to do because of your genes. If you did not have the genes for a human brain, you wouldn't be able to make decisions like you do now. And also, genes are constantly being translated into proteins that keep you alive, the process is not rigid and still responds to stimuli. So it does maintain a level of control that you do not have (you cannot will cancer away just because you want to). If you have "good genes" it means your set of genes makes a machine that is good at survival and reproduction.

Although it isn't really "foresight". Imagine asking a billion people to take a test without telling them what they'll be tested on. And then tell them if they fail they'll die. That's like natural selection. No gene can see the future and be like, right, I better modify myself a little bit and tell my neighbours to change A, B, C and D to prepare for the ice age. It's basically a lot of genes that make a lot of machines and some machines don't do well for whatever reason. So in hindsight, it seems as if the genes really have some sort of foresight, but of course they don't. So when I said a gene is pulling tricks, it really isn't. It was just "lucky" (by chance), to land beside a useful gene and therefore gets passed on when that useful gene is passed on.

And I apologize, shouldn't have said ultimate goal of evolution, I meant ultimate result of evolution will be that genes that are good at survival and passing themselves on will be around and others wouldn't. You can't say the same for machines, because machines will die out. Longevity of machines is not selected for after reproductive age. But longevity of genes is however the result of a gene that builds machines (along with other genes) that propagates it. Even though natural selection and evolution do not have purposes, natural selection does select for certain things. We used to think that natural selection will select for the phenotype that's best for species survival. In the selfish gene theory, natural selection selects for genes. It's the same process, but two different ways of understanding it. One of it sees it from the viewpoint of the organism, the other sees it from the viewpoint of the genes.

Hope that's not too convoluted.

That makes a lot of sense and I think I have a clearer understanding now...but a couple more questions. When the genes of the father and the genes of the mother produce a new genome, how is it decided which of the genes will be recessive? Also, does this mean genetic diversity increases with each new individual (that might be an obvious yes) and if so, is there a "capping" off where a phenotype deletes certain genetic material to reduce diversity? (that's probably another obvious yes but it brings me to one last question)...what determines which genes will be deleted? Is it random or is there some selective pressure? What is it? If it happens to be neighbors with other "good" genes? I apologize if these questions sound convoluted (your answers, I appreciate, are not).

Whether which gene will be recessive depends on the gene itself. There are different scenarios.

Example: 2 types of alleles in this particular gene. We'll call them A and B. The A allele is dysfunctional and doesn't get translated into proteins. The B allele codes a functional protein. So we have 3 possibilities: AA, AB, BB. In the case of AB, do you think the phenotype would resemble AA or BB? It would resemble BB because one B allele is enough to make enough proteins to manifest similar phenotypes as BB.

It's similar types of scenarios, sometimes one allele makes a dysfunctional protein except in the presence of another protein, etc. etc. And it's not as clean cut as they make it sound like in high school. There are genes with addition effect as well. So if a gene codes for melanin (for example, completely fictional), having 6 of it gives you a darker skin colour. Having 3 gives you a medium tone. And so on. So it doesn't have to be one gene dominant another recessive.

About genetic diversity, yes provided that the new organism is actually genetically diverse. In incest the diversity goes down every generation. Look into conservation science if you're interested in that, they talk about the minimum number of genetically diverse individuals you need to keep a population self sustainable.

There is a cut off to how many genes you can carry. Prokaryotes don't have a lot of genes because of size and maintenance takes energy that may be better spent elsewhere. That's partly why bacteria evolve so much quicker. Selection is very strong because genes keeps getting chucked away.

Selection isn't random. If you have a genetic disease and can't survive till reproduction your genes die with you. If that genetic disease is so deleterious that everyone with that defect dies before reproducing, you can imagine that it is strongly selected against, since it's chances of getting replicated is significantly lowered. Deletion/mutation is random, but whether the machine survives the mutation isn't random. If it's a silent gene (used to be known as junk DNA, now they're not sure if it's junk), anyway, if it's truly junk, deletion makes no difference. So as time goes along, deletion of that gene is likely to happen (this goes into probabilities). However if the same random deletion/mutation happens to an important gene, it would cause the death of the machine, causing that mutation to be selected against. If you look into genetics people talk about genes that are "highly conserved", meaning you find the same genes in almost all members of the species, it would mean the gene is really essential for survival. [/quote]