High School

In hummingbirds, feather color is incompletely dominant. A population of hummingbirds has 396 red-sided individuals (RR), 257 brown-sided individuals (Rr), and 557 tan-sided individuals (rr). Calculate the following:

a. What is the allele frequency of the R allele (p)?

b. What is the allele frequency of the r allele (q)?

c. Using the allele frequencies above (p and q), what is the predicted frequency of RR individuals in the next generation?

d. Using the allele frequencies above (p and q), what is the predicted frequency of Rr individuals in the next generation?

e. Using the allele frequencies above (p and q), what is the predicted frequency of rr individuals in the next generation?

Answer :

Final answer:

The allele frequency of the R allele is 0.547 and the allele frequency of the r allele is 0.311. The predicted frequency of RR individuals in the next generation is 0.298 and the predicted frequency of Rr individuals is 0.339. The predicted frequency of individuals in the next generation is 1.

Explanation:

The allele frequency of the R allele (p) can be calculated by dividing the number of red-sided individuals (RR) by the total number of individuals in the population. In this case, the frequency of the R allele is (396 + 257/2) / (396 + 257 + 557) = 0.547.

The allele frequency of the r allele (q) can be calculated by dividing the number of brown-sided individuals (Rr) by the total number of individuals in the population. In this case, the frequency of the r allele is (257 + 257/2) / (396 + 257 + 557) = 0.311.

Using the allele frequencies above (p and q), the predicted frequency of RR individuals in the next generation can be calculated by multiplying p². So, the predicted frequency of RR individuals is 0.547² = 0.298.

Using the allele frequencies above (p and q), the predicted frequency of Rr individuals in the next generation can be calculated by multiplying 2pq. So, the predicted frequency of Rr individuals is 2 * 0.547 * 0.311 = 0.339.

The predicted frequency of individuals in the next generation can be calculated by adding the frequencies of RR, Rr, and rr individuals. So, the predicted frequency of individuals in the next generation is 0.298 + 0.339 + 0.363 = 1.

To get allelic and genotypic frequencies in a population, we need to know the total number of individuals, and the number of individuals with each genotype. a) f(R) = p = 0.433. b) f(r) = q = 0.566. c) F(RR) = p² = 0.1875. d) F(Rr) = 2pq = 0.49. e) F(rr) = q² = 0.32.

What are allelic and genotypic frequencies?

When talking about frequencies, we are referring to proportions. In this case, the proportion of alleles and genotypes in a population. They provide an idea if alleles and genotypes are common or rare in a certain population.

Since it is a proportion, we need to count how many times the same allele or the genotype appears among all individuals and then divide that number by the population size. Remember that in proportions, the lowest limit is 0, while the highest limit is 1.

Following the Hardy-Weinberg equations, we can calculate allelic frequencies and genotypic frequencies if we know the number of individuals with a genotype in a population.

Hardy-Weinberg equations,

Assuming diallelic genes expressing complete dominance

  • p + q = 1 ⇒ being p and q allelic frequencies
  • p² + 2pq + q² = 1 ⇒ being p², q², and 2pq genotypic frequencies

→ Allelic frequencies

  • Dominant allele ⇒ f(X) ⇒ p
  • Recessive allele ⇒ f(x) ⇒ q

→ Genotypic frequencies

  • Homozygus dominant ⇒ F(XX) ⇒ p²
  • Heterozygous ⇒ F(Xx) ⇒ 2pq
  • Homozygous recessive ⇒ (F(xx) ⇒ q²

Genotypic frequencies,

Nº of individuals with a certain genotype / Total number of individuals

In the exposed example, the phenotypes are red, brown, and tan-sided. Brown is the intemediate phenotype expressed by heterozygous individuals.

  • 396 red-sided individuals (RR),
  • 257 brown sided individuals (Rr)
  • 557 tan-sided individuals (rr)
  • Total number of individuals 1210

We will use these equations to answer the questions.

a. What is the allele frequency of the Rallele (p)?

  • RR frequency = F(RR) = 396/1210 = 0.327
  • Rr frequency = F(Rr) = 257/1210 = 0.212
  • rr frequency = F(rr) = 557/1210 = 0.46

The frequency of the R allele, f(R), equals the addition of F(RR) + 1/2 F(Rr)

f(R) = F(RR) + 1/2F(Rr)

f(R) = 0.327 + 0.212/2

f(R) = p = 0.433

b. What is the allele frequency of the r allele?

The frequency of the r allele, f(r), equals the addition of F(rr) + 1/2 F(Rr)

f(r) = F(rr) + 1/2F(Rr)

f(r) = 0.46 + 0.212/2

f(r) = q = 0.566

c. Using the allele frequencies above (p and q), what is the predicted frequency of RR individuals in the next generation?

F(RR) = p² = 0.433² = 0.1875

d. Using the allele frequencies above (p and q), what is the predicted frequency of Rr individuals in the next generation?

F(Rr) = 2pq = 2 x 0.433 x 0.566 = 0.49

e. Using the allele frequencies above (p and q), what is the predicted frequency of rr individuals in the next generation?

F(rr) = q² = 0.566² = 0.32

You can learn more about allelic and genotypic frequencies at

https://brainly.com/question/17008537

#SPJ4