Which of the following cannot occur if a population is to...

Which of the following cannot occur if a population is to maintain an equilibrium of allele frequencies? a. People leave one country and relocate in another. b. A disease wipes out the majority of a herd of deer. c. Members of an Indian tribe allow only the two tallest people in the tribe to marry each spring. d. Large black rats are the preferred males in a population of rats. e. All of these are correct

Which of the following cannot occur if a population is to maintain an equilibrium of allele frequencies?
a. People leave one country and relocate in another.
b. A disease wipes out the majority of a herd of deer.
c. Members of an Indian tribe allow only the two tallest people in the tribe to marry each spring.
d. Large black rats are the preferred males in a population of rats.
e. All of these are correct

Key Concepts

Natural and Sexual Selection

Natural and sexual selection are processes where certain traits become more or less common based on their impact on survival and reproduction. When certain phenotypes are favored, the allele frequencies shift accordingly, which is contrary to the assumption of no selection in a population at Hardy-Weinberg equilibrium.

Hardy-Weinberg Equilibrium

This principle states that in an ideal population—with conditions such as no mutation, migration, selection, genetic drift, and random mating—allele and genotype frequencies remain constant from generation to generation. It forms the foundation for understanding when and how evolutionary processes impact genetic variation in populations.

Gene Flow

Gene flow refers to the movement of individuals, and thereby alleles, between populations. This migration can introduce new alleles into a population or remove existing ones, thereby disrupting the equilibrium predicted by the Hardy-Weinberg model.

Genetic Drift

Genetic drift is the random fluctuation of allele frequencies from one generation to the next, especially pronounced in small populations. Events such as random death or a bottleneck effect (like a disease wiping out a large portion of a population) can significantly alter genetic variation and lead to deviations from equilibrium.

Nonrandom Mating

Nonrandom mating occurs when individuals in a population do not pair by chance, but instead choose mates based on specific traits or conditions. This preferential selection can change genotype frequencies and disrupt the balance assumed by Hardy-Weinberg, as it effectively increases the chances of certain alleles being passed on over others.

Transcript

00:02 Okay, so our question here, which of the following cannot occur if a population is to maintain an equilibrium of allele frequencies? equilibrium, you should immediately think of the hardy -winberg equilibrium, which was highlighted earlier in this chapter.

00:21 And so this hardy -wineberg equilibrium is very important for calculating gene frequencies in alleles and genotypes.

00:29 But it only works if there is no evolution occurring.

00:34 And remember that evolution is a change in allele frequencies.

00:37 So basically what this question is asking is how can we deviate from the hardy weinberg condition? basically, what would make evolution occur? so if we go and review this table that is on page 283 of your textbook, we can look at the different conditions that...

01:00 That will make a population deviate from hardy winebird equilibrium so first we have random mating remember we have these peppered moths somewhere dark somewhere light and if dark moths are only mating with dark moths then we have non -random mating and this means a change in allele frequencies has evolution occurred no that's because we specifically define evolution as a change in allele frequencies, but it is still enough to avoid the hardy -winberg equation.

01:37 We can use it to compare it.

01:39 Okay, the next is no selection.

01:42 So there can't be any selection.

01:43 So here we have the dark moth and the light moth on the tree, and here we have the tree swallow, only selecting the dark moth, because that's what they can see.

01:52 And this is a form of selection, a change in allele frequencies.

01:54 Evolution has occurred and therefore the hardy -wy -wy equation doesn't work.

02:01 Again, now we have mutation.

02:05 The addition of new alleles to the population will change the allele frequencies.

02:11 Next we have no migration.

02:13 That's immigration or emigration.

02:16 Once individuals carry alleles into or out of the population, we have a change in allele frequencies, which again is evolution.

02:22 And finally, we have a large population.

02:24 We need a large population so that genetic drift does not act on the population.

02:29 And remember, genetic drift can have a bottleneck effect or a founder effect.

02:34 And this is a loss in alleles diversity...

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