Ch 23

Question 1

Genetic Variation

Answer 1

makes evolution happen

Question 2

Microevolution

Answer 2

change in allele frequency in pop. over generation

Question 3

Mechanisms that change allele frequency

Answer 3

-natural selection
-genetic drift
-gene flow

Question 4

Genetic drift

Answer 4

-change in frequency of an existing gene variant in pop. due to random chance
-significant in small pop.
-causes allele frequencies to change at random
-lead to loss of genetic material within pop.
-can cause harmful alleles to become fixed
-reduces genetic variation

Question 5

Gene flow

Answer 5

-transfer of genetic material from one pop. to another
-tends to reduce variation of pop. over time
-can bring crappy genes which may decrease fitness
-may also increase fitness

Question 6

Discrete characters

Answer 6

either/or bases (have/don’t have widows peak)

Question 7

Quantitative

Answer 7

vary along a continuum within pop. (height)

Question 8

Geographic variation

Answer 8

-differences between gene pools of separate pop.
-exhibited by most species

Question 9

cline

Answer 9

-graded change in a tree along a geographic axis
-ex. of example of geographic variation

Question 10

Mutation

Answer 10

-Change in nucleotide sequence
-chromosome mutations that delete, disrupt, and rearrange loci are typically harmful
-duplication of small pieces increases genome size (usually less harmful)
-rate is low in animals/plants, lower in prokaryotes and higher in viruses

Question 11

Point mutation

Answer 11

-Change in one base in a gene
-harmless in non-coding regions
-can be neutral due to redundancy
-may be harmful/beneficial if result in change in proteins

Question 12

Duplicated genes

Answer 12

take on new functions by further mutation

Question 13

Sexual reproduction

Answer 13

can shuffle existing alleles into new combinations

Question 14

Population

Answer 14

-Localized group of individuals capable of interbreeding and producing fertile offspring
-same species in same place

Question 15

Gene pool

Answer 15

Consists of all alleles for all loci in population

Question 16

Locus

Answer 16

Fixed if all individuals in a population are homozygous for same allele

Question 17

Hardy-Weinberg Equation

Answer 17

-always=1
-describes pop that is not evolving
-if doesn’t meet criteria, then pop. is evolving

Question 18

Criteria for Hardy-Weinberg equation

Answer 18

-no mutations
-Random mating
-no natural selection
-extremely large population
-no gene flow

Question 19

Hardy-Weinberg principle

Answer 19

States the frequencies of alleles in genotype in a population remain constant from generation to generation
-allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences.

Question 20

Founder effect

Answer 20

-part of genetic drift
-and reduction in genomic variability that occurs when a few individuals become isolated from a larger pop.

Question 21

Bottleneck effect

Answer 21

-sudden reduction in population size due to changes in the environment
-result in gene pool may not be the same as original

Question 22

Bottleneck effect

Answer 22

-sudden reduction in population size due to changes in the environment
-result in gene pool may not be the same as original

Question 23

Relative fitness

Answer 23

Contribution in individual makes to gene pool of next generation

Question 24

3 modes of selection

Answer 24

-directional
-disruptive
-stabilizing

Question 25

direction selection

Answer 25

favors individuals of a certain phenotype

Question 26

disruptive selection

Answer 26

Favors individuals at both extremes of phenotypic range

Question 27

stabilizing selection

Answer 27

Favors intermediate (middle) variants and acts against extreme phenotype

Question 28

sexual selection

Answer 28

-natural selection for mating success
-intrasexual selection
-intersexual selection

Question 29

intrasexual selection

Answer 29

Competition among individuals of one sex, often in males, for mates of opposite sex (1 male lion with dozen lionesses, another male finds group, both males fight)

Question 30

Intersexual selection

Answer 30

-Usually females are choosy and selecting their mates
-also called mate choice
-male showiness increases chances of attracting female

Question 31

sexual dimorphism

Answer 31

Marked differences (in size or appearance) between sexes (male or female)

Question 32

Neutral variation

Answer 32

Genetic variation that doesn’t confirm a selective advantage or disadvantage

Question 33

Diploidy

Answer 33

Maintains genetic variation in form of hidden recessive alleles

Question 34

Balancing selection

Answer 34

Occurs when natural selection maintains stable frequencies of two or more phenotypic forms in a population
-include heterozygote advantage and frequency-dependent selection

Question 35

Heterozygote advantage

Answer 35

Occurs when heterozygotes have a higher fitness than the both homozygotes
-heterozygous sickle cell individuals are less susceptible to malaria

Question 36

Frequency-dependent selection

Answer 36

Fitness of phenotype declines if it becomes too common in population

Question 37

Frequency-dependent selection

Answer 37

Fitness of phenotype declines if it becomes too common in population