mkwiki Генетски дрифт; mswiki Hanyutan genetik; nlwiki Genetische drift; nnwiki Gendrift; nowiki Genetisk drift; plwiki Dryf genetyczny; ptwiki Deriva genética. Many translated example sentences containing “dryf” – English-Polish dictionary and search engine (proces określany jako „dryf genetyczny”), jak również [ ]. Zmienność genetyczna populacji znajduje się z kolei pod wpływem naturalnych procesów ewolucyjnych, takich jak dobór naturalny, dryf genetyczny i przepływ.
|Published (Last):||27 July 2015|
|PDF File Size:||16.34 Mb|
|ePub File Size:||18.42 Mb|
|Price:||Free* [*Free Regsitration Required]|
Discussions of conditions for Hardy-Weinberg. Genetic drift, bottleneck effect, and founder effect.
genetic drift – Wikidata
Natural selection in populations. Selection and genetic drift. Transkrypcja filmu video Voiceover: What I want to do with this video is explore the idea of allele frequency. Just as a reminder, an allele is a variant of a gene. You get a variant of a gene from your mother, and you get another variant of the gene from the father. So, when we’re talking about the allele, we’re talking about that specific variant that you got from your mother or your father.
We’ve seen this before, but now let’s dig a little bit deeper. To help us get our heads around this, we’ll start with a fairly common model for this. We’re going to think about eye color. Obviously, this is a very large simplification, but let’s just assume geentyczny we have a population where there’s only two variants of an eye color gene. Let’s first assume there is an eye color gene. Let’s assume there’s two variants. One genegyczny, one allele for eye color, we’ll use the shorthand, capital B.
Let’s say that’s the allele for brown. We’re going to assume that this one is dominant. It’s dominant over the other allele. Now the other allele, we’re going to assume is for blue eye color, and we’ll represent that with a lower case B.
So that is blue eye color, and we’re going to assume that this is recessive. Once again, this is review.
Someone who has one of the big B alleles, the brown alleles, it doesn’t matter what their other allele is going to be, because it’s either going to be another brown or eryf going to be a blue, they’re going to show brown eyes.
This is going to be brown eyes, and this is going to be brown eyes, because the capital B is dominant.
The only way to get blue eyes is to be a homozygote for the recessive allele. All of that, of course, is review. We’ve seen that before. Now let’s think about allele frequency. To think about that, I’ll set up a very artificially small population. Let’s say our population has exactly two people in it. Population has exactly two people in it, Person 1 and Person 2, and let’s say we’re able to look into their DNA and figure out their genotypes. Person 1, say, has a capital B allele, has a brown allele and a blue allele, while Person 2 has two blue, two blue alleles.
Given that we know the genotypes in this artificially small population, we could start thinking about the allele frequencies. Or the frequencies of the different alleles. What do you think is going to be the frequency the frequency of the brown allele in this population? I encourage you to pause this video and think about this on your own.
In allele frequencies, you want to dig a little bit deeper and look at the individual alleles.
When you look at that, you say, “Okay, there’s “four individual alleles in this population, or there’s “four variants, or there’s literally four chromosomes “that are carrying that gene in this population. Now we genstyczny do the same, ask ourselves the same question for the lower case B allele. What fraction of the genes in this population are code for or represent the lower case B, the blue allele?
File:Random sampling genetic – Wikimedia Commons
Once again, I encourage you to pause the video and think about it. Well, very similar idea.
There’s four genes in the population that are coding for eye color. Of them, one, two, three code for or are the lower case blue allele. I really want to hit this point home, how this is different than, say, the phenotype frequency. If I asked you, in the population, if I asked you the percent of brown-eyed people, so now I’m talking about phenotype, what would that be? Well, there’s two people in the population.
One of them is exhibiting brown eyes, so that’s going to be one-half. Similarly, if I were to ask you what is the percentage of people who are blue-eyed that, too, would be one-half. This person is one of the two people, they’re exhibiting blue eyes.
File:Random sampling genetic drift.gif
But allele frequency, we’re digging deeper, we’re looking at the genotypes. This is really important to internalize. Because once we internalize this, then as we’ll see, that the ideas in the Hardy-Weinberg principle start to make a lot of sense. I’ll do a little bit of foreshadowing. We can denote this, this is just a convention that’s often used, by the lower case letter P, and we can use lower case Q to denote the frequency.
So lower case P is the frequency of the dominant allele, lower case Genetycsny the frequency of the recessive allele. I encourage you to pause the video genftyczny and think about that. What is this going to be equal to?
Well, when we started off, we said that there’s only two potential, that’s one of the assumptions we assumed, we assumed there’s only two alleles in this population, in kind of the allele population for this gene population for this trait. We see that there.
Is equal to one. So, in the next video, we’re going to start from the genetyzcny fairly simple idea, to get to a more richer and fairly neat idea that’s expressed in the Hardy-Weinberg equation.