SimBio: genetic drift & bottlenecked ferrets

What is the Founder effect?

a. Sampling error that occurs during the establishment of a new population by a small number of migrants

b. Natural selection that acts on the founders of a new population in their new different environment

c. The frequencies of alleles in a population changing slowly over generations due to chance events

d. A period of rapid population growth that immediately follows some population bottlenecks

a

Which of the following statements about genetic drift and population size is true?

a. If a population is large enough, it will not experience any genetic drift

b. The larger sample is, the less likely it is similar to its source population

c. A population is unlikely to lose genetic diversity when its size is drastically reduced

d. The effects of genetic drift are more pronounced in very small populations

d

What effect does inbreeding have on a population?

a. Inbreeding tends to decrease the effects of sampling error in a population

b. Inbreeding tends to increase the census population size

c. Inbreeding tends to increase the proportion of homozygous individuals in a population

d. Inbreeding tends to decrease a populations susceptibility to disease

c

What is the effective size of a population?

a. The size of a population with the same heterozygosity as the actual population, but which does not lose heterozygosity over time

b. The size of an idealized, random mating population, losing homozygosity at the same rate as the actual population

c. The size of an idealized randomly mating population, losing heterozygosity at the same rate as the actual population

d. The size of a randomly mating population with the same sex ratio as the actual population

c

Which of the following is most likely to increase the effective size of a population?

a. Increasing the census population size and making the sex ratio less balanced

b. Decreasing the census population size and making mating more random

c. Decreasing the census population size and making the sex ratio less balanced

d. Making the sex ratio more balanced and making mating more random

d

If gametes from a gene pool, combine randomly to make only a small number of zygotes, the allele frequencies among the zygotes may be quite different than they are in the gene pool. Why?

a. The effects of natural selection are more pronounced in small populations

b. Change in all frequencies over many generations are inevitable with sexual reproduction

c. Alleles combine more randomly with a small number of zygotes

d. The effects of sampling error are more pronounced with smaller samples

d

How is genetic drift different than natural selection?

a. Natural selection occurs because some alleles higher fitness, whereas genetic drift occurs because of sampling error

b. Natural selection has a stronger effect in large populations, whereas genetic drift acts primarily in small populations

c. Natural selection is a mechanism of evolution, whereas genetic drift is not a mechanism, but an outcome of evolution

d. Natural selection tends to cause very rapid evolution, whereas genetic drift tends to operate on much longer time scales

a

Imagine a population evolving by genetic drift, in which the frequency of alle K is 0.3. What is the probability that at some point in the future allele K will drift to a frequency of 1.0?

0.3

A dwindling population of 1000 frogs occupies an isolated area in Costa Rica. To help preserve the species, scientist caught 20 frogs to start a new population in a nearby area. This species has a gene that affects eye shape. The 1000 member wild population has two alleles for this gene: R and r, with frequencies 0.7 and 0.3, respectively. What will be the allele frequencies of R and r in the 20 member founder population?

a. The frequencies will be 0.7 for R and 0.3 for r

b. The frequencies will be 1.0 for R and 0 for r

c. The expected frequencies are 0.7 for R and 0.3 for r. The actual frequencies could be different.

d. The founder population’s allele frequencies will necessarily be different than the source population’s frequencies

c

For a population containing 90 females and 10 males, what is the effective population size?

36