CH.17: Processes of Evolution

Question 1

What is Microevolution?

Answer 1

• Change in allele frequencies in a population or species.
• Individuals of a natural population share morphological, physiological, and behavioral traits and characteristics of the species.
• Different alleles are the basis of differences in the details of a population’s shared trait.
• All allele frequencies (microeveolution) is always occuring in the gene pools of natural populations.

Question 2

What is Allele Frequency?

Answer 2

Abundance of a particular allele among members of a population.

Question 3

What is Gene Pool?

Answer 3

All the alleles of all the genes in a population; a pool of genetic resources.

Question 4

What is Lethal Mutation?

Answer 4

Mutation that darastically alters phenotype; cause death.

Question 5

What is Nuetral Mutation?

Answer 5

A mutation that has no effect on survival or reproduction.

Question 6

What is a Population?

Answer 6

A group of organisms of the same species that live in a specific location and breed with one another more often than they breed with members of other populations.

Question 7

What is Genetic Equilibrium?

Answer 7

Theoretical state in which a population is not evolving.

Question 8

How do we know a population is evolving?

Answer 8

• Researchers measure genetic change by comparing it with a theoretical baseline of genetic equilibrium.
• Genetic equilibrium never occurs in natural populations because ideal conditions can never be met.

Question 9

Does evolution occur in recognizable patterns?

Answer 9

Natural selection, the most influential process of evolution, occurs in patterns that depend on the organisms and their environment.

Question 10

What is Directional Selection?

Answer 10

• Mode of natural selection in which phenotypes at one end of a range of variation are favored.
• Causes allele frequencies underlying a range of variation to shift in a consistent direction.

Question 11

What is Disruptive Selection?

Answer 11

• Mode of natural selection that favors forms of a trait at the extreme end of the range of variation; intermediate forms are selcted against.

Question 12

What is Stabalizing Selection?

Answer 12

• Mode of natural selection in which intermediate forms of a trait are favored over extremes.
• Presereves the midrange phenotype in a population.

Question 13

What is Balanced Polymorphism?

Answer 13

Maintenance of two or more alleles for a trait at high frequency in a population as a result of natural selection against homozygotes.

Question 14

What is Sexual Dimorphism?

Answer 14

• Distant male and female phenotypes.
• Individuals of one sex (often males) tend to be more colorful, larger, or more aggressive than individuals of the of the other sex.

Question 15

What is Sexual Selection?

Answer 15

• Mode of natural selection in which some individuals outreproduce others of a population because they are better at securing mates.
• The most adaptive forms of a trait help individuals defeat same-sex rivals for mates, or are the ones most attractive to the opposite sex.

Question 16

What is a bottleneck?

Answer 16

Drastic reduction in population size as a result of severe selection pressure.