Question

any help would be appreciated.

After reading the following prompt, propose a scientific study to determine whether or not evolution is occurring. In your answer, include the type of data you will need to collect, and the calculations you will use to figure out if the mechanism at work is natural selection or genetic drift. Is this population genetics research or quantitative genetics research? Case #2: In elephants, trunks comes in a variety of lengths such that this trait exhibits a continuously variable phenotype: long, short, and everything in between. The size of an elephant's trunk is determined by several genes, but it can also be influenced by environmental factors. The average trunk length in a population of elephants 20 years ago was 1.4 meters.

Question 1

After reading the following prompt, propose a scientific study to determine whether or not evolution is occurring. In your answer, include the type of data you will need to collect, and the calculations you will use to figure out if the mechanism at work is natural selection or genetic drift. Is this population genetics research or quantitative genetics research?

Case #1: In population of lilies, two alleles are responsible for the production of flower color. The dominant allele produces a violet phenotype, while the recessive allele produces a yellow phenotype. Ten years ago the frequency of the violet allele was 0.62 and the frequency of the yellow allele was 0.38.

Question 2

After reading the following prompt, propose a scientific study to determine whether or not evolution is occurring. In your answer, include the type of data you will need to collect, and the calculations you will use to figure out if the mechanism at work is natural selection or genetic drift. Is this population genetics research or quantitative genetics research?

Case #2: In elephants, trunks comes in a variety of lengths such that this trait exhibits a continuously variable phenotype: long, short, and everything in between. The size of an elephant’s trunk is determined by several genes, but it can also be influenced by environmental factors. The average trunk length in a population of elephants 20 years ago was 1.4 meters.

Answer 1

Case I:

Calculation before data collection :

The allele Frequencies of dominant and recessive allele are known. From that we can calculate the genotypic frequencies of homozygous dominant individuals (p2) which are violet, heterozygotes (2pq) which are violet and homozygous recessive individuals (q2) which are yellow.

Data collection :

We need take a significant population size for sampling (say N = 1000) and randomly select individuals. Phenotype and genotype of each of the individuals need to collected. In addition, we need to observe if the environmental conditions or the habitat in which the plants are found favour the violet phenotype or yellow phenotype.

Calculation after data collection :

Now we calculate the genotypic frequencies (p'2 , q'2 , 2p'q' of each genotype by using the following formula :

Number of samples of concerned genotype/ Total sample size (here N = 1000)

After calculating the genotypic frequencies , we can derive the allele frequencies (p' and q') by taking square roots of p'2 and q'2 .

Analysis :

Now the change in allele frequency can be calculated by subtracting the allele frequencies. This helps to infer if natural selection or genetic drift has occurred or not. If there is a significant change (p >0.05) in allele frequency, then we can predict that natural selection has occurred.

If the change in the allele frequency of any one of the allele is drastic and it appears that the allele is leading towards fixation (p = 1 or q = 1) then we can infer that probably genetic drift is acting on the population.

This is a population genetics research.

Case II :

From the given information , it is easy to infer that the research is a quantitative genetics research since the traits which need to be observed are continuous in nature.

Data collection :

First we need to collect as many phenotype continuous variations in the elephant population by taking a significant sample size (say N = 150). The data collected has to be random and unbiased. The information of trunk sizes or the measurements of trunk sizes need to be Organized into separate categories such as long, short, moderate,etc. Now from the sample of population the complete genetic analysis of a significant number of individuals ( say 50) need to be done to know which genes are involved in determining the trunk length. In addition, we need to collect the data on several environmental parameters such as tree height, environment type, temperature of habitat, presence of mutagens, etc. to account for the genetic variance resulting from environmental factors.

Calculation :

After the determination of genes, the contribution of each allele (for ex -additive effect of allele) need to be calculated by comparing each genotype with trunk length. For ex - If genotype AABBCC has a trunk length of 1.2 m and aabbcc has a trunk length of 0.6 m and the each A allele has an additive effect , then contribution of each A allele will be = (1.2 - 0.6) / 6 = 0.1 m. Using this calculation , contribution of each allele needs to be calculated.

Analysis :

In order to see if natural selection is happening, we need to find out if any single or similar genotypes (say moderate trunk length) has higher frequency of occurrence than the other continuous variations. In addition to that, we need to find the probable advantages conferred by moderate trunk length to the individuals which may lead to higher reproductive success.

In order to see if genetic drift is working, the genotypic frequencies can be compared. If any single or similar genotype and corresponding phenotype are favoured and there is significant difference between them and other genotypes, then we can predict that genetic drift is working.