Unit 3 - Evolutions in Populations

Question 1

What is a population?

Answer 1

A group of individuals of the same species that live in the same area and interbreed.

Question 2

____ are composed of populations of individuals.

Answer 2

Species

Question 3

What is an allele?

Answer 3

Genetic variants on loci.

Question 4

What is frequency?

Answer 4

The proportion of the population with that genotype of allele.

Question 5

What is a gene pool?

Answer 5

It consists of all copies of every allele at the loci of interest in all members of the population.

Question 6

What are polymorphic populations?

Answer 6

When a population or gene pool has more than one allele.

Question 7

What are monomorphic populations?

Answer 7

When a population or gene pool has only one allele. Allele is “fixed”.

Question 8

What is evolution at the scale of a population defined as?

Answer 8

A chance in allele frequency over generations.

Question 9

What is allele frequency?

Answer 9

The proportion of a specific allele out of the total number of alleles in the gene pool.

Question 10

In a gene pool, there are 20 B alleles and 80 b alleles. What is the frequency of the “b” allele?

Answer 10

0.8

Question 11

What is evolution?

Answer 11

The change in allele frequency over generations.

Question 12

What does the frequency of all alleles add up to?

Answer 12

One.

Question 13

At a locus with two allele, p = 0.65. What is q?

Answer 13

0.35

Question 14

What are the four processes that change allele frequencies?

Answer 14

Mutation, drift, migration, and selection.

Question 15

In a population of 320 red flowers(CRCR), 20 white flowers(CWCW), and 160 pink flowers(CRCW), how many CW alleles are there?

Answer 15

200

Question 16

When can you calculate expected genotype frequencies?

Answer 16

When the allele frequency is known in the parental population and when there is random mating in the parental population.

Question 17

What is random mating?

Answer 17

When every individual has as equal and independent chance of mating with every other individual.

Question 18

What is the rule of probability?

Answer 18

If samples are drawn at random, the probability of a given item being included in the samples equals the frequency of that item in the source population.

Question 19

What does the Hardy-Weinberg equation predict?

Answer 19

Genotype frequencies from allele frequencies. (p^2 +2pq + q^2)

Question 20

What type of population will genotype and allele frequencies will be constant under the Hardy-Weinberg model?

Answer 20

A population that is not evolving and randomly mating.

Question 21

What can the Hardy-Weinberg equation test?

Answer 21

Whether a population is evolving or not.

Question 22

When there is a significant deviation from HWE, what does it suggest?

Answer 22

One of the HWE assumptions were violated.

Question 23

What do we assume with HWE?

Answer 23

There is no selection, no mutation, no migration, a large population, and random mating.

Question 24

Approximately ___ of the US population carry PKU alleles.

Answer 24

2%

Question 25

What are allele frequencies?

Answer 25

The proportion that allele makes up of the total.

Question 26

What can genotype frequencies do?

Answer 26

They will rapidly achieve HWE for a given set of allele frequencies.

Question 27

What is evolution?

Answer 27

A change in allele frequencies in a population over time.

Question 28

What are random processes?

Answer 28

Processes that can have different outcomes, but cannot be predicted.

Question 29

What is an example of a random process?

Answer 29

Flipping a coin.

Question 30

What is genetic drift?

Answer 30

It is the random change of allele frequencies from one generation to the next due to random events.

Question 31

What is a haploid?

Answer 31

An individual that has only a single copy of their genes.

Question 32

What causes random sampling in real populations?

Answer 32

Any process that has the effect of randomly increasing or decreasing allele frequencies.

Question 33

What is the meiosis lottery?

Answer 33

One large source of random sampling.

Question 34

What are the two main facts about drift?

Answer 34

1. It is the main driver of evolution at the genetic level. 2. It is the null hypothesis when testing for other evolutionary processes.

Question 35

Drift causes _____ changes from generation to generation in smaller populations.

Answer 35

Extreme

Question 36

What is fixation?

Answer 36

When the allele frequency of one allele reaches 100%, also occurs more rapidly in small populations.

Question 37

What are the two forms are genetic drift?

Answer 37

Founder effect and bottleneck effect.

Question 38

What is the found effect?

Answer 38

Occurs when a small number of individuals become isolated from a larger population.

Question 39

Island populations have much ____ genetic diversity vs. the mainland.

Answer 39

Lower

Question 40

What is the bottleneck effect.

Answer 40

A magnification of the effect of genetic drift due to a reduction in size within a population.

Question 41

Where does the bottleneck effect occur?

Answer 41

Within a single population.

Question 42

What does genetic drift do to evolution?

Answer 42

- Makes the evolutionary process more random - Reduces genetic variation - Can result in the fixation of alleles.

Question 43

What is gene flow?

Answer 43

The movement of alleles between populations due to migration.

Question 44

What is migration?

Answer 44

The movement of an individual from one population to another.

Question 44

Gene flow tends to make populations __________ over time.

Answer 44

more genetically similar

Question 44

If all gene flow between two populations suddenly stopped, we would expect them to start becoming ___ different over time.

Answer 44

more

Question 44

Isolation by distance is a pattern of _____ genetic differences with ____ geographic distance.

Answer 44

increasing; increasing

Question 45

What is genetic swamping?

Answer 45

The reduction in a population’s ability to adapt due to gene flow from a maladapted population.

Question 46

What is adaptive introgression?

Answer 46

The movement of beneficial alleles between populations, which facilitates adaptation.

Question 47

What is FST?

Answer 47

A measure of genetic differences between populations. Ranges between 0 and 1.

Question 48

What is natural selection?

Answer 48

The differential survival and reproduction of individuals/genotypes due to differences in phenotype.

Question 49

True/False: No other evolutionary process causes adaptation.

Answer 49

True.

Question 50

What are the basic requirement for evolution via natural selection.

Answer 50

1. There is phenotypic variation in the population. 2. The variation is at least somewhat heritable. 3. The variation results in differences in fitness.

Question 51

What is fitness?

Answer 51

A quantitative measure of how much an individual with a particular phenotype or genotype will contribute to the next generation on average.

Question 52

True/False: Strength, intelligence, speed, etc. is not necessarily connected to evolutionary fitness.

Answer 52

True.

Question 53

What are the three main forms of selection?

Answer 53

Directional selection, disruptive selection, and stabilizing selection.

Question 54

What is directional selection?

Answer 54

An increase in the frequency of a trait or allele due to a fitness benefit.

Question 55

Directional selection tends to ____ genetic variation.

Answer 55

reduce

Question 56

What is disruptive selection?

Answer 56

Changes in population genetics in which extreme values for a trait are favored over intermediate values

Question 57

What is stabilizing selection?

Answer 57

The population mean stabilizes on a particular non-extreme trait value.

Question 58

What is balancing selection?

Answer 58

Selection that maintains two or more phenotypic forms in a populations.