Question

A rare cactus from Arizona (Echinocactus horizonthalonius) has only five known populations. One of these populations was monitored over five years in the early 1990s with 2, 3, 25, 32, and 86 plants recorded. The effective population size (Ne) is 5.48 while the average population census size (Nc) is 29.6. a. Give a biological explanation for the difference between these two estimates. b. Why is effective population size an important measurement for natural populations? Use the example above to support your answer.

Answer 1

b) Because of most of the large populations, it looks good to ask if genetic drift is really all that necessary. Most populations are large is correct, but they don't be show large necessarily. Therefore, genetic drift rate is not actually proportional to census population size (N_c). Preferably, it's proportional to the effective population size (N_e).

In small population, genetic processes lie on the effective population size comparatively than the number of individuals. The Ne estimates its genetic behaviour, compared to an ideal population. Ne can be measured from demographic data on population size fluctuate over generations, sex-ratio and variance in sizes of family.