Lecture 3

Question 1

What are different components of logistic growth?

Answer 1

1. Initial exponential growth
2. Decline in growth rate (due to resource limitations and (in)direct competition)
3. Zero growth rate at the carrying capacity (i.e. the number of organisms that can be supported without environmental degredation)

Question 2

What conditions are needed for natural selection?

Answer 2

1. Reproduction
2. Heredity
3. Variation in heritable traits
4. Variation in fitness

Question 3

What is the definition of fitness?

Answer 3

Relative reproductive success due to a heritable trait

Question 4

What is needed to produce a phenotype?

Answer 4

Phenotype = Genotype + Environment

Question 5

What is the definition of a phenotype?

Answer 5

External characteristics of an individual that selection can act on

Question 6

What is the definition of a genotype?

Answer 6

Sets of genes (heritable “instruction”) carried by the individual; the genetic makeup

Question 7

What statistics are used to describe the frequency distribution of a heritable trait?

Answer 7

1. Average
2. Variance

Question 8

What is the definition of statistical average?

Answer 8

The measure of the central tendency of a population

Question 9

What is the definition of statistical variance?

Answer 9

The measure of the spread around the average

Question 10

What are the 2 categories of variation?

Answer 10

1. Continuous variation
2. Discrete variation

Question 11

What is the definition of continuous variation?

Answer 11

Types of variations are distributed on a continuum (quantitative traits); the combined effect of many genes (i.e. polygenic); environment influences trait variation

Question 12

What is the definition of discrete polymorphisms?

Answer 12

Related to multiple forms of a gene that can exist (qualitative traits); based on a single major gene (i.e. monogenic); environment plays no role

Question 13

What is the definition of heritability?

Answer 13

The fraction of the total phenotypic variance that is attributable to genetic differences among individuals in a given population

Question 14

What is the significance of heritability?

Answer 14

Heritability is evidence of

Question 15

Variance equation:

Answer 15

V_p = V_g + V_e + V_g*e

V_p = tot phenotypic variance

V_g = variance due to differences in genetic factors

V_e = variation due to environmental influence

V_g*e = variation due to interactions between genes and the environment

Question 16

Heritability equation:

Answer 16

H² = V_g/V_p

Question 17

What does low heritability mean?

Answer 17

1. Little genetic variation in the population
2. Greater environmental induced variation than genetic control

Question 18

What does it mean when H² is equal to 0?

Answer 18

There is no genetic variation (still a heritable trait and has a genetic basis) and the population is under fixation. HOWEVER, environmental induced variation can still occur

Question 19

What are the different types of selection?

Answer 19

1. Directional selection
2. Stabilizing selection
3. Disruptive selection
4. No selection

Question 20

What is the definition of directional selection?

Answer 20

A mode of natural selection in which an extreme phenotype is favored over the others, causing allele frequencies to shift over time in that direction

Question 21

What is the definition of stabilizing selection?

Answer 21

A mode of natural selection in which the population mean stabilizes on a particular non-extreme (median) trait value

Question 22

What is the definition of disruptive selection?

Answer 22

A mode of natural selection in which extreme values for a trait are favored over the intermediate value

Question 23

What is the definition of heredity?

Answer 23

Refers to inheritance (i.e. the transfer of genetic information from parent to offspring)

Question 24

What is the definition of population think?

Answer 24

The theory that regularities that occur in populations such as extiction, speciation, and adaptation emerge from the collective activities of individuals

Question 25

What is the definition of differential survivorship?

Answer 25

Shows how some survive better than others - population starts off with 50% A and 50% B, but when observed at a different time, some of A die while B remains the same

Question 26

What is the definition of differential reproduction?

Answer 26

Starting with a population balanced 50/50, both increase in number, but B adds more to the population (increases more in frequency in relation to A)

Question 27

What is the definition of biological evolution?

Answer 27

An inherited change in a group of variable organisms through time

Question 28

What is GWAS (Genome-Wide Association Study) used for?

Answer 28

GWAS looks at genetic variants underlying a trait variation, and determines which are statistically significant and which are not

Question 29

How are SNPs used in GWAS?

Answer 29

SNPs are used to correlate genetic variations with phenotypic variations

Question 30

What type of study is GWAS?

Answer 30

Observational study

Question 31

What can serve as a result for disruptive selection?

Answer 31

Disruptive selection often occurs during speciation events