Chapter 23

Question 1

Microevolution

Answer 1

Evolutionary change below the species level; change in allele frequencies in populations over generations

Question 2

3 main mechanisms that cause change in allele frequencies

Answer 2

1) Natural selection
2) genetic drift
3) gene flow

Question 3

Genetic Variation

Answer 3

Differences among individuals in the composition of their genes/DNA sequences

Question 4

Introns

Answer 4

Non coding segments of DNA lying between exons

Question 5

Exons

Answer 5

Regions retained in mRNA after RNA processing

Question 6

Without genetic variation…

Answer 6

Evolution cannot occur

Question 7

Neutral Variation

Answer 7

Result of point mutation, genetic variation that doesn’t provide a selective advantage or disadvantage

Question 8

Point mutation

Answer 8

A very small mutation, such as a change in one base in a gene

Question 9

Gene pool

Answer 9

The aggregate of all copies of every type of allele at all loci in every individual in a population

Question 10

Adaptive evolution

Answer 10

A process in which traits that enhance survival/reproduction tend to increase in frequency over time

Question 11

Generic drift

Answer 11

Chance events cause unpredictable fluctuations in allele frequencies from one generation to the next

Question 12

Founder effect

Answer 12

Genetic drift that occurs when few individuals become isolated from a larger population and form a new population who’s gene pool doesn’t reflect original population

Question 13

Bottleneck effect

Answer 13

Genetic drift that occurs when the size of a population is reduced by natural disasters or human effect. Surviving population usually doesn’t reflect original population

Question 14

Genetic drift is..,

Answer 14

1) significant in small populations
2) cause alleles to change at random
3) lead to a loss of genetic variation within populations
4) cause harmful allele to become fixed

Question 15

Gene flow

Answer 15

Transfer of alleles from one population to another, resulting from movement of fertile individuals or their gamates

Question 16

Relative fitness

Answer 16

Contribution an individual makes to the gene pool of the next generation

Question 17

Directional selection

Answer 17

Form of natural selection in which individuals at one end of phenotypic range survive or reproduce more then others

Question 18

Disruptive selection

Answer 18

Natural selection in which individuals on both extremes of a phenotypic range survive or reproduce more then Individuals with intermediate phenotypes

Question 19

Stabilizing selection

Answer 19

Natural selection in which intermediate phenotypes survive or reproduce more then extreme phenotypes

Question 20

Sexual selection

Answer 20

Process in which individuals with certain inherited characteristics are more likely to obtain mates then others of the same sex

Question 21

Sexual dismorphism

Answer 21

Differences between the secondary sex characteristics of males and females of same species (think male female peacocks)

Question 22

Intrasexual selection

Answer 22

Direct competition between the same sex to find a mate

Question 23

Intersexual selection

Answer 23

Individuals of one sex (usually females) are very choosy in selecting opposite sex mate (aka mate choice)

Question 24

Balancing selection

Answer 24

Natural selection that maintains two or more phenotypic forms in a population

Question 25

Frequency-dependent selection

Answer 25

Selection in which fitness of phenotype depends on how common the phenotype is in population

Question 26

Heterozygote advantage

Answer 26

Greater reproductive success of heterozygous individuals compared to homozygous