Chapter 23

Question 1

what 4 processes drive evolution

Answer 1

1. natural selection
2. genetic drift
3. gene flow
4. mutation

Question 2

how does natural selection drive evolution

Answer 2

increases frequency of certain alleles

Question 3

how does genetic drift drive evolution

Answer 3

allele frequencies change randomly

Question 4

how does gene flow drive evolution

Answer 4

individuals leave one population, join another, and breed; introduce different alleles

Question 5

how does mutation drive evolution

Answer 5

modifies allele frequencies by continually introducing new alleles

Question 6

what did Hardy and Weinberg calculate

Answer 6

what would happen if pairs of gametes are plucked at random out of a gene pool and then form offspring

Question 7

do allele frequencies change over time

Answer 7

NO

Question 8

what does a null hypothesis specify

Answer 8

what should be observed if hypothesis being tested is NOT correct

Question 9

what does nonrandom mating cause

Answer 9

only genotype frequencies to change, not allele frequencies unless it occurs with other processes

Question 10

what does inbreeding lead to

Answer 10

• increase in homozygosity of population
• leads to decrease in average fitness via selection

Question 11

what is the most extreme form of inbreeding

Answer 11

self fertilization

Question 12

does inbreeding cause evolution

Answer 12

no because allele frequencies do not change in population as a whole

Question 13

how does inbreeding influence evolution

Answer 13

increases the rate at which natural selection eliminates recessive deleterious alleles from a population
- speed up rate of evolutionary change

Question 14

when does nonrandom mating occur due to sexual selection

Answer 14

occurs sometimes because an organism actively choses a certain mate based on it’s physical and/or behavioral traits

Question 15

what does natural selection violate

Answer 15

assumptions of Hardy-Weinberg

Question 16

what combines to cause natural selection

Answer 16

ecological selection + sexual selection

Question 17

what are the 4 main patterns of natural selection

Answer 17

1. directional
2. stabilizing
3. disruptive
4. balancing

Question 18

when is genetic drift random

Answer 18

in respect to fitness- changes in allele frequency that it produces are not adaptive

Question 19

when is genetic drift most pronounced

Answer 19

in small populations

Question 20

over time, what can genetic drift lead to

Answer 20

random loss or fixation of alleles
- genetic variation then decreases

Question 21

what causes genetic drift in natural populations

Answer 21

founder effect and bottleneck effect

Question 22

what outcomes can genetic drift cause on fitness

Answer 22

increase, decrease, or same

Question 23

what causes gene flow

Answer 23

when individual leaves one population, joins another, and breeds

Question 24

is gene flow random

Answer 24

with respect to fitness, yes

Question 25

what ways can mutation occur

Answer 25

- point mutation - chromosome level mutation - lateral gene transfer

Question 26

is mutation fast or slow

Answer 26

slow

Question 27

when can mutation have a large effect on evolution

Answer 27

when combined with genetic drift, gene flow, and selection

Question 28

mutation in evolution

Answer 28

1. mutation is ultimate source of genetic variation 2. mutations are random with respect to fitness 3. if mutation did not occur, evolution would eventually stop 4. mutation alone is usually inconsequential in changing allele frequencies at a particular genre

Question 29

what reduces differences between populations

Answer 29

gene flow

Question 30

what causes populations to diverge

Answer 30

- natural selection - genetic drift - mutation

Question 31

what is genetic drift caused by

Answer 31

sampling error

Question 32

what are the causes of a bottleneck effect

Answer 32

- disease outbreak - natural catastrophes - human catastrophes

Question 33

what occurs in disruptive selection

Answer 33

- competition - abiotic or biotic - eventually lead to different species - increase variation in trait

Question 34

what occurs in balancing selection

Answer 34

maintains "status quo"

Question 35

inter sexual selection involves who in a species

Answer 35

between different sex's - male showing off for female - make and female usually look different

Question 36

intra sexual selection involves who

Answer 36

within a sex - competition for mate - shift in features that allow for better chance to win competiton

Question 37

directional

Answer 37

favors one extreme, shifting the population traits

Question 38

stabilizing

Answer 38

favors average traits, reducing variability