Chapter 9: Genetic Variation and Inbreeding

Question 1

founder effect

Answer 1

the original population could give rise to different founder populations

Question 2

genetic variation

Answer 2

the difference in the genetic makeup (DNA) of individuals or populations among the same species

Question 3

genetic variation is important for….

Answer 3

survival & adaptation

Question 4

what does genetic variation help with?

Answer 4

helps in terms of natural selection and evolution

Question 5

genetic variation

Answer 5

measure of the genetic differences within individuals or population

Question 6

genetic diversity

Answer 6

the genetic variation of an entire species

Question 7

Tasmanian devils

Answer 7

• loss of genetic variation near ext.
• devil facial tumor disease
• contagious cancer
• cancer cells do not recognize as foreign and proliferate

Question 8

effective population size variable

Answer 8

Ne

Question 9

effective population size

Answer 9

the number of individuals that effectively participates in producing the next generation

Question 10

which is smaller - effective population size or census size?

Answer 10

effective population size

Question 11

small Ne

Answer 11

bigger increase in genetic drift

Question 12

Ne and sex ratio

Answer 12

Ne is highest at equal breeding sex ratio

Question 13

types of genetic variation

Answer 13

• intrapopulation
• interpopulation

Question 14

intrapopulation

Answer 14

• within population
• amount of variation within the members of a species in the same area

Question 15

interpopulations

Answer 15

• between populations
• comparing two or more populations of a species

Question 16

what determines levels of genetic variation in populations?

Answer 16

• mutation
• genetic drift
• gene flow
• sexual selection
• natural selection

Question 17

levels of genetic variation that cause rapid and powerful phenotypic changes on management-relevant time scales

Answer 17

• genetic drift
• gene flow
• natural selections

Question 18

mutation definition

Answer 18

random change in the DNA of a gene

Question 19

mutation functions

Answer 19

• can form new allele
• can be passed on to offspring if in reproductive cells

Question 20

genetic drift

Answer 20

• change in allele frequencies by chance
• genetic drift causes a loss of genetic diversity
• it is most common in small populations

Question 21

what can lead to genetic drift

Answer 21

a population bottleneck

Question 22

when does a bottle neck occur?

Answer 22

when an event drastically reduces population size

Question 23

is Ne greater or smaller than N

Answer 23

Ne < N

Question 24

how to measure genetic drift?

Answer 24

• depends on the effective population size
• essentially the number of individuals in a population who contribute offspring to the next generation

Question 25

gene flow definition

Answer 25

the movement of alleles between population

Question 26

when does gene flow occur

Answer 26

when individuals join new populations and reproduce

Question 27

gene flow keeps neighboring populations ____

Answer 27

similar

Question 28

low gene flow

Answer 28

increases the chance that two populations will evolve into different species

Question 29

sexual selection occurs when:

Answer 29

- certain traits increase mating success - there is higher cost of reproduction for females - males produce many sperm continuously - females are more limited in clutch size

Question 29

sexual selection

Answer 29

non-random mating

Question 30

intrasexual selection

Answer 30

competition among males

Question 31

intersexual selection

Answer 31

males display certain traits to females

Question 32

what does natural selection act on?

Answer 32

distributions of traits

Question 33

natural selection acts on distribution of traits

Answer 33

- highest frequency near mean value - frequencies decrease toward each extreme value

Question 34

natural selection can take one of three paths

Answer 34

- directional selection - stabilizing selection - disruptive selection

Question 35

interbreeding

Answer 35

loss of heterozygosity and increased expression of recessive homozygotes

Question 36

F IS

Answer 36

inbreeding due to preferential mating with relatives

Question 37

F ST

Answer 37

inbreeding due to genetic drift in a small population mating randomly

Question 38

inbreeding coefficient

Answer 38

a measure of loss of heterozygosity = increase of homozygosity

Question 39

what is one form of inbreeding?

Answer 39

genetic drift

Question 40

symbol for inbreeding due to genetic drift

Answer 40

F ST

Question 41

F ST range

Answer 41

0 - 1

Question 42

F ST range: 0

Answer 42

- no loss of heterozygosity - all populations have the same allele frequencies

Question 43

F ST range: 1

Answer 43

- complete loss of heterozygosity - fixation of one or another allele in each population

Question 44

F ST increases _________ when Ne is small

Answer 44

rapidly

Question 45

F ST = 1 - [1 - (1/2 Ne)] ^t

Answer 45

expression showing increase in F ST among completely isolated populations of different size

Question 46

inbreeding depression

Answer 46

the loss of heterozygosity and expression of deleterious recessive alleles due to inbreeding disturbs vital rates

Question 47

examples of inbreeding depression

Answer 47

births & deaths

Question 48

inbreeding due to genetic drift is ________ by ____________

Answer 48

reduced by gene flow

Question 49

what gets washed out if there is too much gene flow?

Answer 49

local selection

Question 50

calculating allele frequencies

Answer 50

allele frequencies measure genetic variation

Question 51

allele frequencies measure genetic variation

Answer 51

- measure how common an allele is in a population - can be calculated for each allele in a gene pool

Question 52

population

Answer 52

a freely interbreeding group of individuals

Question 53

gene pool

Answer 53

the sum total of genetic information present in a population at any given point in time

Question 54

phenotype

Answer 54

a morphological, physiological, biochemical, or behavioral characteristic of an individual organism

Question 55

genotype

Answer 55

the genetic constitution of an individual organism

Question 56

locus

Answer 56

a site on a chromosome, or the gene that occupies the site

Question 57

gene

Answer 57

a nucleic acid sequence that encodes a product with a distinct function in the organism

Question 58

allele

Answer 58

a particular form of a gene

Question 59

gene (allele) frequencies

Answer 59

the relative proportion of a particular allele at a single locus in a population

Question 60

genotype frequency

Answer 60

the relative proportion of a particular genotype in a population

Question 61

natural selection paths - directional selection

Answer 61

favors phenotypes at one extreme

Question 62

natural selection paths - stabilizing selection

Answer 62

favors the intermediate phenotype

Question 63

natural selection paths - disruptive selection

Answer 63

favors both extreme phenotypes