Unit I: Intro to Evolution

Question 1

What is evolution?

Answer 1

change in allele frequencies of a population across generations

Question 2

What processes cause evolution?

Answer 2

1. Natural selection
2. Genetic drift
3. Migration
4. Mutation

Question 3

What is Natural Selection?

Answer 3

1. reproduction of individuals with favorable genetic traits that survive environmental change because of those traits, leading to evolutionary change

Question 4

What is Variation?

Answer 4

genetic differences among individuals in a population

Question 5

What are the 4 Postulated of Natural Selection?

Answer 5

1. Variation exists among individual organisms in a population
2. Some of that variation is heritable
3. Survival and reproduction success is variable
4. Individuals best able to survive and reproduce is not a random sample

Question 6

Explain Postulate 3 of Natural Selection.

Answer 6

• Populations produce more offspring than can survive
• Resource limit populations, lead to struggle for existence
• Some individuals reproduce more than others

Question 7

What is a Polygenic Trait?

Answer 7

controlled by multiple genes
(ex: expressions of Bmp4 which effects width and depth)

Question 8

What is Adaptation?

Answer 8

heritable traits or behavior in an organism that aids in its survival and reproduction in its present environment
Note: that environments change, and thus the trait that is adaptive can also change

Question 9

What is Heredity?

Answer 9

the transmission of genetic characteristics from parents to offspring

Question 10

What is heritability?

Answer 10

the fraction of population variation that can be attributed to its genetic variance

Question 11

What did Gregor Mendel discovery?

Answer 11

(1822-1884)
- Each parent passes a combination of discrete ‘factor’ (alleles or genes)
- Each gamete carries only one factor
-Factors segregate independently during gamete formation
- Dominant and recessive factors

Question 12

Was Gregor Mendel’s work known by Wallace and Darwin?

Answer 12

Yes

Question 13

What is Evolutionary Fitness?

Answer 13

individual’s ability to survive and reproduce

Question 14

What is Relative Fitness?

Answer 14

individual’s ability to survive and reproduce relative to the rest of the population

Question 15

What is Selection Pressure:

Answer 15

environmental factor that causes one phenotype to be better than another (abiotic or biotic)

Question 16

Name the types of Selections.

Answer 16

1. Stabilizing selection
2. Directional selection
3. Diversifying selection
4. Frequency-dependent selection
5. Negative free-dependent selection
6. Sexual selection
7. Artificial selection

Question 17

In Stabilizing selection, Phenotype higher AND lower than the mean has __________.

Answer 17

low fitness

Question 18

In Stabilizing selection, mean __________________.

Answer 18

stays the same

Question 19

In Stabilizing selection, Genetic variation is _______.

Answer 19

reduced

Question 20

In Directional selection, Phenotype higher OR lower than the mean has _______.

Answer 20

highest fitness

Question 21

In Directional selection, the mean move in the direction with the ______ fitness.

Answer 21

higher

Question 22

In Directional selection, Genetic variation is _______.

Answer 22

reduced

Question 23

In Diversifying selection, Phenotype higher AND lower than the mean has the ____ fitness

Answer 23

high

Question 24

In Diversifying selection, the mean ___________________.

Answer 24

COULD stay the same

Question 25

In Diversifying selection, Genetic variation is ________.

Answer 25

increased

Question 26

Positive frequency-dependent selection is understood to be

Answer 26

stabilizing selection

Question 27

What is Negative frequency-dependent selection?

Answer 27

is a type of diversifying selection when considered over multiple generations

Question 28

In Negative frequency-dependent selection the ____ type has a higher fitness.

Answer 28

rare

Question 29

In populations with sexual dimorphism, the ____ are typically more decorated, larger , or stronger.

Answer 29

males

Question 30

What is Sexual Selection?

Answer 30

selection that favors phenotypes that increase ability to obtain or choose good mate

Question 31

Who does Sexual Selection often act on? And Why?

Answer 31

Males, because of fundamental asymmetry of sex

Question 32

What is Fundamental Asymmetry of Sex?

Answer 32

females invest more in their offspring than do males

Question 33

What does Sexual Selection predict?

Answer 33

females should be choosy, males compete with each other

Question 34

What is Artificial Selection?

Answer 34

Deliberate manipulation of fitness by humans through selective breeding

Question 35

What type of Selection molds domesticated plants and animals?

Answer 35

Artificial Selection

Question 36

What leads to genetic drift?

Answer 36

sampling error in sexual reproduce

Question 37

Individuals are ______ & produce gametes that are ______.

Answer 37

diploid (2n), haploid (n)

Question 38

Gametes contain _________ of an individual's alleles

Answer 38

random sampling (50/50 probability for each allele)

Question 39

Allele frequencies therefore ______ across generations.

Answer 39

"drift"

Question 40

The magnitude of the drift is INVERSELY related to the population size:

Answer 40

large population size = low genetic drift small population size = high genetic drift

Question 41

Genetic Drift can lead to _____ or ____ of alleles, which reduces genetic diversity.

Answer 41

loss (freq = 0), fixation (freq = 1)

Question 42

What causes Genetic Drift?

Answer 42

1. Bottleneck effect (sudden reduction in population size) 2. Founder Effect (dispersal over a barrier)

Question 43

Genetic drift affects the whole genome and is random with respect to fitness.

Answer 43

True

Question 44

Genetic drift will usually result in a _______ in average fitness.

Answer 44

reduction