You are studying a population of parrots. The parrots are generally either whist

Question

You are studying a population of parrots. The parrots are generally either whistlers, squawkers or are able to do both with this trait controlled by a gene at a single locus. Parrots with WW genotype are whistlers. Those with ww are squawkers and those with Ww are able to make both sounds. You assume that the parrots are in Hardy-Weinberg equilibrium. You take a survey of the parrots and find the following numbers:

whistlers: 4900

squawkers: 900

both: 4200

a) Calculate the genotype and allelic frequencies in this population of parrots.

Genotypic frequency of homozygous recessive squawkers (ww)= q^2 = 900/ 10000 = 0.09

Allelic frequency of squawkers (w) = 0.09= q = 0.3

Genotypic frequency of whistlers (WW)= p^2 =4900/ 10000 = 0.49

Allelic frequency of squawkers (W) = p = 0.49 = 0.7

Frequency that make both sounds (Ww)= 2pq =2 * 0.7 * 0.3 = 0.42

Hardy-Weinberg equilibrium check= p^2 + 2pq + q^2 = 0.49 + 0.42 + 0.09 = 1

b) The population of parrots you are studying is becoming popular in the pet trade and are being trapped by poachers. Whistling parrots are the most desirable and so are being lost from the population in the greatest numbers. One year after poaching began you find the following numbers of parrots: whistlers: 500

squawkers (ww): 3000

both: 4000

What are the genotype and allelic frequencies in your population of parrots in this year after poaching begins?

Genotypic frequency of homozygous recessive squawkers (ww)= q^2 = 3000/ 7500 = 0.4

Allelic frequency of squawkers (ww) = 0.4= q = 0.632

Genotypic frequency of whistlers (WW)= p^2 =500/ 7500 = 0.06

Allelic frequency of whistlers (W) = p = 0.06 = 0.245

Frequency that make both sounds (Ww)= 2pq =2 * 0.245 * 0.632 = 0.310

Hardy-Weinberg equilibrium = p^2 + 2pq + q^2 = 0.06 + 0.310 + 0.4 = 0.769 (due to poaching)

Using the information that I calculated above, how do I figure out the absolute and relative fitness of each genotype? Including calculation of mean fitness, what allelic frequencies would you expect following another year of poaching?

Explanation / Answer

The survival or reproductive rate of a genotype or phenotype with respect to the maximum survival or reproductive rate of other genotypes in the population,is termed as Relative Fitness.

Thus, relative fitness of genotype whistlers will be equal to 500/4000, i.e., 0.125

Relative fitness of genotype squawkers (ww) will be equal to 3000/4000, i.e., 0.75, and

Relative fitness that make both sounds (Ww) will be equal to 4000/4000, i.e., 1.0

For mathematical purposes, absolute fitness is standardized to get relative fitness.

Thus the heterozygous is the most fit genotype among the population.

Survival rate is the overall survival rate in percentage of individuals born that survive to reproductive age.

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