Practice Exam Questions Week 5

Question 1

Why is it likely that MOST speciation is allopatric?

Because related species are always found in allopatry rather than in sympatry.

Because gene flow between diverging populations is strong in allopatry.

Because gene flow between populations prevents genetic divergence in sympatry.

Because vicariance events are common.

Because disruptive selection between forms of traits in sympatric populations is always very strong.

Answer 1

Because gene flow between populations prevents genetic divergence in sympatry.

Question 2

In general, sympatric speciation requires the action of _____ selection acting against hybrids.

artificial

stabilizing

directional

disruptive

ecological

Answer 2

disruptive

Question 3

A large population of mice (2000 individuals) lives in an area dominated by small shrubs in the desert. When the population size got too high, a small group of 6 individuals left and colonized an area adjacent to the original population’s home, but this area is primarily dominated by trees instead of shrubs. There is no gene flow between the dispersers and the original population. A researcher sequenced the genomes of representative individuals from both populations and found substantial genetic differences between them. Which of the following would MOST account for the amount of genetic differences observed?

Divergence between the two groups is high because of gene flow between them.

Divergence between the two populations was caused solely by drift.

The divergence between populations could only have been caused by stabilizing selection.

Since the original dispersal event, the small population will have evolved more than the large population.

Answer 3

Since the original dispersal event, the small population will have evolved more than the large population.

Question 4

In some large groups of plants, including dandelions, oaks, and willows, the biological species concept is complicated because the process of _____ allows gene flow to occur between good _____ that can be easily distinguished based on appearance.

hybridization; morphospecies

allopatric speciation; ring species

hybridization; ecological species

polyploidy; evolutionary species

polyploidy; ring species

Answer 4

hybridization; morphospecies

Question 5

New species can form through allopatric or sympatric speciation. Which of the following mechanisms will act more strongly on populations that are initially separated in allopatry than on those initially separated in sympatry?

disruptive selection

reinforcement

genetic drift

gene flow

Answer 5

genetic drift

Question 6

All else being equal, selection should more strongly favor reinforcement of reproductive isolation among related species in:

peripatric populations over allopatric populations.

sympatric populations over allopatric populations.

peripatric populations over sympatric populations.

allopatric populations over sympatric populations.

allopatric populations over peripatric populations.

Answer 6

sympatric populations over allopatric populations.