Evolution - Ch 23 - Evolutionary Processes

Question 1

How do we know whether evolution or biased mating is occurring?

Answer 1

Hardy-Weinberg Principle

Question 2

What are the 4 modes of natural selection?

Answer 2

directional selection, balancing selection, stabilizing selection, disruptive selection

Question 3

Which sex is more affected by sexual selection, and why?

Answer 3

sexual selection acts more strongly on males than females since any allele that increases a male’s attractiveness or success in intrasexual competition should quickly pop up in a population

Question 4

What is the Hardy-Weinberg equilibrium equation (for two traits, p and q)

Answer 4

p^2 + 2pq + q^2 = 1

[p + q = 1]

Question 5

What is purifying selection, and what mode of selection does it fall under?

Answer 5

disadvantageous alleles tend to decrease in frequency, and fall to 0 frequency (while favoured alleles become fixed)

Question 6

What is a gene pool?

Answer 6

all the alleles of all the genes of a certain population

Question 7

What is genetic variation?

Answer 7

the number and relative frequency of alleles present in a population

Question 8

What does stabilizing selection do? How does it affect genetic variation?

Answer 8

selects against both extremes

-decrease in genetic variation

Question 9

What does disruptive selection do? How does it affect genetic variation?
What can it lead to?

Answer 9

(opposite of stabilizing) the middle is selected against

• increases genetic diversity
• can lead to speciation

Question 10

What does balancing selection do? How does it affect genetic variation?

Answer 10

no alleles have a distinguishable advantage, at all times

-genetic variation stays the same

Question 11

What can cause balancing selection?

Answer 11

• heterozygote advantage

- frequency-dependent selection

Question 12

What is frequency-dependent selection?

Answer 12

when specific alleles are favoured when rare, but disadvantageous when common

Question 13

What is genetic drift? What populations are most affected by it?

Answer 13

the change in allele frequency in a population, by chance

-is significant in smaller populations

Question 14

What is genetic drift? What populations are most affected by it?

Answer 14

the change in allele frequency in a population, by chance

-is more significant in smaller populations

Question 15

What is genetic drift? What populations are most affected by it?

Answer 15

the change in allele frequency in a population, by chance
-is more significant in smaller populations
-

Question 16

What is genetic drift? What populations are most affected by it?

Answer 16

the change in allele frequency in a population, by chance

-is more significant in smaller populations (more prone to fixation/loss of alleles)

Question 17

How is the genetic variation of a population affected by natural selection, genetic drift, genetic flow, and mutations?

Answer 17

• natural selection: depends on mode
• genetic drift: neutral
• genetic flow: increase or decrease
• mutations: increase

Question 18

How is the genetic variation of a population affected by natural selection, genetic drift, genetic flow, and mutations?

Answer 18

• natural selection: depends on mode
• genetic drift: neutral
• genetic flow: increase or decrease
• mutations: increase

Question 19

What is a founder event, and what is the founder effect?

Answer 19

• founder event: when a group of individuals immigrate to a new geographical area to start a new population
• founder effect: when a founder event occurs that causes a change in allele frequencies (compared to the original population) due to sampling error of small population

Question 20

What is a population bottleneck, and what is a genetic bottleneck?

Answer 20

• population bottleneck: when a large population suddenly loses a high number of individuals
• genetic bottleneck: when a great amount of alleles decrease in number, which by chance likely changes the allele frequency of the population and decreases genetic variation

Question 21

What is gene flow?

Answer 21

the movement of alleles between populations when an individual migrates between them

Question 22

What is the ultimate source of genetic variation?

Answer 22

mutations

Question 23

What is a chromosome-level mutation?

Answer 23

the change in number of composition of chromosomes, which can duplicate genes, leading to loss of function or new alleles

Question 24

What is a lateral gene transfer?

Answer 24

the movement of genes from one species to another

Question 25

How quickly does mutations cause evolution

Answer 25

very slowly, by itself it is not a significant factor of evolution

Question 26

What are some types of biased mating?

Answer 26

inbreeding and assortative mating

Question 27

Does inbreeding or assortative mating cause evolution?

Answer 27

NO because they only change genotype frequencies, not allele frequencies

Question 28

What is inbreeding depression?

Answer 28

the decrease in average fitness when homozygosity increases and heterozygosity decreases (caused by close relatives mating with each other) -occurs because many recessive alleles represent loss of function mutations

Question 29

What is assortative mating? What is positive assortment, and what is negative assortment?

Answer 29

when mates are chosen based on certain traits - positive: when individuals tend to mate with those with a shared phenotypic trait as them - negative: when individuals tend to mate with those with a different specific phenotypic trait

Question 30

What is sexual selection? Can it cause evolution? What are the two types?

Answer 30

The favouring of individuals with traits that increase their ability to attract mates or choose good mates. Yes, it causes evolution. -intersexual choice and intrasexual selection

Question 31

What is intersexual choice?

Answer 31

when an individual of one sex (females usually0 chooses a specific indivudual of the other sex for mating

Question 32

What is intrasexual selection?

Answer 32

selection driven by competition among members of one sex (males usually) for an opportunity to mate

Question 33

What is the pattern and process of the animal theory of The Fundamental Asymmetry of Sex?

Answer 33

- pattern: traits that attract the opposite sex are much more gaudy/elaborate in males - process: eggs are more expensive energy-wise than sperm are

Question 34

What is sexual dimorphism?

Answer 34

any trait that differs between males and females