Roman and Palumbi (2003; Example 12.2) used the amount of genetic variation at m

Question

Roman and Palumbi (2003; Example 12.2) used the amount of genetic variation at mtDNA to estimate the historical effective population sizes of three species of whales in the North Atlantic using the following expression: H = N_e mu/N_e mu + 1) = theta/theta + 1 They then adjusted these estimates of N_c to provide estimates of historical census population sizes, N_C. Their estimates of N_C are far greater than the current estimates that are used in the management and conservation of these species. Recovery goals for these species are based upon the estimated carrying capacity which has been assumed to be approximately equal to historical population sizes. (a) What are the three primary weaknesses of the estimates by Roman and Palumbi? Briefly explain each of these. (b) Assume that you are hired as a consulting geneticist by the International Whaling Commission (IWC) to evaluate this paper. Write a brief statement to the IWC that evaluates the validity of the estimates of Roman and Palumbi. Remember, the members of the IWC are not geneticists. Your statement should provide them with your evaluation of the validity of these estimates and discusses their primary weaknesses.

Explanation / Answer

(a) 1. There is an uncertainity in the generation length of whales. What was the average generation time of males and females was not clealy pointed out. The generation time has to interact with the mutation rates to determine actual population size in long term.

2. There was no accurate estimate of mutaion rate in the population. Their mutation rate estimate was low by two fold due to multiple substitutions in the fastly evolving control region of mtDNA, as discovered in future studies.

3. There was only mtDNA based estimate which was unsuccessful to predict long term historical census population size. Instaed the use of Multilocus Nuclear Estimates can give more accurate results, because nuclear DNA has relatively less saturation of substitutions than mtDNA.

(b) Estimates of Roman and Palumbi are solely mtDNA based and depend upon control region mutation only.

The mutation rate estimated by them has proved to be two times slower than the rate of mutations estimated by further studies because fastly evolving mtDNA control region undergoes multiple substitutions in long run.

Although they used a wide range of generation length of whales (about 12 to 24 years), still the generation time of the whales remains unknown.

They found that there was a vast abundance of whales ( in about 150-250 thousands numbers range) prior to whaling. And the inaccuracy in long term abundance estimates was due to uncertain catching records.

Related Questions

Navigate

• Browse (All)
• Browse R
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.