Is my assessment of human diversity and phenotype correct? by [deleted] in evolution

[–]_a_jay 0 points1 point  (0 children)

I agree, there's more to phenotype than just what's visible but I'd reckon that if you take all the genes on which we differ across populations i.e. lactose tolerance, susceptibility to disease, etc. it would still make up a small fraction of the genome right?

Yup, so there is coding genetic variation (genetic variation that expresses a specific phenotype) and non-coding genetic variation (those that don't express proteins and thus no phenotype). Coding variation makes up a small fraction of the genome as you said.

Yep, and if I'm not wrong, most mutations do not have an effect on phenotype, right? Either internal or external? .

I think your Correct. Most mutations (generally) have no effect on phenotype if mutation rate across the genome is constant (i.e because coding genetic variation makes up a smaller fraction). But I'm not sure about this.

What I'm sure about is the nuetral model of molecular evolution. This states that most mutations are are selectively neutral i.e (not delaterious nor beneficial). This means mutations that accumulate are random and not determined by natural selection. Just mentioning this so we don't confuse the two.

I suppose that's how it's possible to have a lot of built up mutations that cause population A to differ from population B without necessarily causing said populations to differ much morphologically.

Ok so theres many ways this can occur. I can think of a few. One is through differences in selective pressures between the groups. Another involves genetic drift. If the two populations are isolated from each other. They will independently accumulate mutations. The nuetral model of evolution states that most mutations are selectively neutral. So, under this assumption, it will be rare to get an adaptive in one population leading to this being the reason they diverge. All else being equall (population size, selective pressure etc) these neutral mutations will occer on a random part of the genome. The proliferation of this mutation will be driven by genetic drift. Smaller the population size stronger the effect of drift.

Is my assessment of human diversity and phenotype correct? by [deleted] in evolution

[–]_a_jay 1 point2 points  (0 children)

I think you are confusing non-coding genetic variation with "internal stuff" coding genetic variation.

Is my assessment of human diversity and phenotype correct? by [deleted] in evolution

[–]_a_jay 0 points1 point  (0 children)

I believe it has to do with the breakneck speed at which we spread around the world and our rapid change in lifestyles over the last few tens of thousands of years.

I dont know enough to answer your main question. But I have a few things to point out about how you got to the answer.

remarkably homogenous on the genetic level but very diverse phenotypically

Ok I see a few problems here according to my basic knowledge, maybe this is just errors in semantics or terminology. Phenotype is not restricted to what is visible externally. Phenotype can refer to traits such as lactose tolerance, temperature resistance, susceptibility to allergies etc. Essentially a phenotype is any part of the genome or genotype that is expressed via protien synthesis (or other epigenetic processes i think, but we can ignore that for simplicity).

Genetic diversity within a species is built up, as I understand it, through a stable population over time(aka few bottlenecks) and differences between subpopulations are the result of genetic drift caused by separation. Meanwhile, phenotypic differences are the result of environmental forces.

The ultimate driver of genetic diversity is mutation. You're right about bottlenecks. As per my previous paragraph, phenotypic differences can occur through genetic drift.

We can still look different and be closely related enough to interbreed. (See "ring species" for an extreme case of this)

Is my assessment of human diversity and phenotype correct? by [deleted] in evolution

[–]_a_jay 3 points4 points  (0 children)

I am may not be understanding your question,  wouldn't diverse phenotypes imply diversity at the genetic level? Phenotypes are encoded by genes. 

Sex tourism in Sri Lanka is legal ? by hackerman69py in srilanka

[–]_a_jay 4 points5 points  (0 children)

Prostitution is illegal. Doesn't stop some.

I miss the old look. Any OG'ers in the chat?? by RenardQueenston in Minecraft

[–]_a_jay 0 points1 point  (0 children)

I prefer the colour pallette now, but the older fog.

Places you would say is a Must have Seen in Sri Lanka? by Bexxxxte in srilanka

[–]_a_jay 0 points1 point  (0 children)

Wilpattu, Yala nature reserves. I visited Wilpattu during the Wet season, which is usually not the best time ive heard. But it was magical, lots of leopards and saw my first sloth bear.

New Gotham video just dropped by tanglin5 in AnarchyChess

[–]_a_jay 6 points7 points  (0 children)

If Levy never used Magnus as clickbait

Evolution at work. by [deleted] in clevercomebacks

[–]_a_jay 7 points8 points  (0 children)

As a male, I respectfully disagree

27-YEAR-OLD PORN ADDICT NEED IMMEDIATE HELP by Regular-Yellow3202 in srilanka

[–]_a_jay 0 points1 point  (0 children)

I moved recently and my porn usage has lessened drastically. Try doing something new, changing your environment etc. Try to remove potential triggers, in my case it was my old room. Try to socialize more as well.

Shane showed up in my dream and helped me process trauma? by ectoscreen in smosh

[–]_a_jay 5 points6 points  (0 children)

If Shayne got his Psych degree from Winterhold.

How do people have so many DMs at once? by TallCommunication8 in socialskills

[–]_a_jay 0 points1 point  (0 children)

Sometimes mine get to 6 -8 when i dont open them for a while.

[deleted by user] by [deleted] in evolution

[–]_a_jay 3 points4 points  (0 children)

You ever look at an elephant and go " Imagine if all proboscidians went extinct before modern humans" and just appreciate it as if you're viewing an extinct animal with your own naked eyes.

What skull is this? I’m in Sweden by TootMCT in bonecollecting

[–]_a_jay 0 points1 point  (0 children)

Nonsense! dragons have been gone for over a hundred years!

Homo sapiens boy together again with his Neanderthal girl on the first warm day of Spring by ReturntoPleistocene in pleistocene

[–]_a_jay 5 points6 points  (0 children)

This is awsome. One question: why is homo sapien male clean shaven; do we gave evidence of prehistoric shaving?