Chapter 11: The Evolution of Populations

The combined alleles of all the individuals in a population are called the

• phenotype

• gene pool

• mutation rate

• allele frequency

What are two main sources of genetic variation?

• mutations and extinction

• recombination and extinction

• recombination and production

• mutations and recombination

Figure 11.1 shows how a population of cacti changes when it faces selective pressure from two predators: peccaries (wild pigs) and a parasitic insect. The dashed line shows the original population. The insects most often kill cacti with a(n)

• intermediate number of spines

• high number of spines

• low number of spines

• complete lack of spines

What type of selection occurs when individuals in a population with the intermediate phenotype are selected for?

• directional selection

• stabilizing selection

• intermediate selection

• disruptive selection

Figure 11.2 shows the tail feather length of male widowbirds and their reproductive success. The males that had the greatest reproductive success were the birds with tails that were

• particularly short

• mid-length

• relatively long

• any length

When a few individuals start a new colony it most likely results in

• genetic drift through the founder effect

• more variety in the new population

• extinction due to the bottleneck effect

• mutation due to disruptive selection

The movement of alleles from one population to another is called

• founder effect

• microevolution

• genetic drift

• gene flow

A population that has a normal distribution of the range of heights has many individuals who are

• tall and few who are average or very short

• short and few who are average or very tall

• average height and few who are very tall or very short

• average height and none who are vey tall or vaery short

What does being in Hardy-Weinberg equilibrium mean for a population?

• the population is evolving very rapidly

• the population is not evolving

• equilibrium would gradually end

• gene flow would occur, but slowly

If the actual allele frequencies in a population do not match genotype frequencies predicted by the Hardy-Weinberg equation, the population is

• isolated

• extinct

• shrinking

• evolving