Theme 4c Pt 1

Question 1

What is genetic drift

Answer 1

A process that is independent of phenotype/alleles and is random. Sampling error

Change in alleles frequencies due to chance in finite populations (small populations)

Question 2

When does genetic drift have the most effect

Answer 2

When the populations are small

Less variance in a small population

Question 3

If you only have one allele for a gene what does this mean for its heterozygosity

Answer 3

There is not heterozygosity

Question 4

What does it mean when an allele (A) is fixed

Answer 4

If the allele is fixed over time, it is constant, so the other allele (a) is eliminated.

A/A

Question 5

What does it mean when an allele (A) is eliminated

Answer 5

The other alleles is fixed (a) and the (A) is gone forever

Question 6

What happens to elimination and fixation in larger populations

Answer 6

The allele gets neither fixed or eliminated since the population is big. It’s stays relatively the same frequency

Question 7

What is bottleneck

Answer 7

Temporary reductions in population size that cause drift and reduce variation because only the alleles of the small remaining population is present.

This causes genetic differences between populations.

Question 8

What causes genetic drift

Answer 8

The founder effect

Bottleneck

Question 9

What is the founder effect

Answer 9

When New populations are started from a small number of individuals leaving the larger group

Depending on the alleles they take with them some can be fixed and some eliminated

Question 10

What does genetic drift do to genetic variation in populations?

Answer 10

Reduces genetic variation and causes populations divergence

Question 11

What is interbreeding

Answer 11

Mating with relatives

Question 12

What is outbreeding

Answer 12

Mating with non relatives (less closely related)

Question 13

What is assortative mating

Answer 13

Individuals with similar geno/phenotypes mate with each other (rather than others) more than expected under a random mating pattern

Question 14

What is non random mating

Answer 14

Choosing to Mate with individuals that are more or less closely related than those from a random mating population

Question 15

What causes inbreeding and why is it HWE violation

Answer 15

Small populations
Mating system (mating with relatives, cousins)

Choosing to Mate more frequently

Question 16

Does inbreeding affect allele and genotype frequencies

Answer 16

No just genotype. Allele frequency’s are not changed

Question 17

What is the consequence of inbreeding, why

Answer 17

Reduced fitness, because rare deleterious alleles are more likely to combine in homozygotes.

They lose heterozygosity and become homozygous recessive

Question 18

What are the three types of natural selections

Answer 18

Directional
Stabilizing (aka balancing)
Disruptive

Question 19

What is directional selection

Answer 19

Individuals of a certain extreme phenotype are favoured

Individuals at one end have higher fitness and other end has lower fitness

The trait mean shifts toward one end

Question 20

What is stabilizing selection

Answer 20

Individuals with intermediate phenotype are favoured (grey moths) and extremes phenotype are selected against (black white moths)

Variance decreases between generations, but the trait mean doesn’t change

Heterozygote advantage

Question 21

What is an example of the advantage in stabilizing selection

Answer 21

Sickle cell anemia, extreme SS phenotype had more extremes anemia but heterozygote AS have mild condition

AA extreme get ver bad malaria

Question 22

What is balancing selection

Answer 22

It is like stabilizing selection, selecting against one extreme for a period of time then eventually selecting against the other extreme

Looks like directional selection in short term

Question 23

What is disruptive selection

Answer 23

Both extreme phenotypes are favoured and the intermediate is selected against

Average individuals have lower fitness, but the trait mean doesn’t change

Question 24

When does natural selection have the most powerful effect

Answer 24

When the population is large

Small advantages in fitness can lead to large changes over the long term

Question 25

What happens when there is no selection

Answer 25

The fitness of each phenotype is equal, no selective pressure

So there is no selection

Question 26

What is viability selection

Answer 26

Ability to survive

Question 27

What is fecundity selection

Answer 27

Ability to reproduce

Question 28

What is sexual monomorphism

Answer 28

When you can’t tell if the species are male of female by their genetalia and phenotype

Question 29

What is sexual dimorphism

Answer 29

When you can tell a difference between a male and female based on genetalia

Question 30

When is natural selection inevitable

Answer 30

When there is variation in phenotype, fitness differences, and inheritance

Question 31

What causes fitness differences

Answer 31

Mating ability, fertilizing ability, fertility, and survivorship

Question 32

What did Darwin do to define selection due to mating and fertilization ability?

Answer 32

Defined it as sexual selection, different than natural selection (heritability)

Question 33

What is the difference between natural and sexual selection

Answer 33

The outcome may be different but the process is the same

Question 34

What is intrasexual selection

Answer 34

Fitness differences that result from the ability of same sex individuals to compete for mating opportunities (male-male competition)

Question 35

What is intersexual selection

Answer 35

Fitness differences that result from choosing specific males and females to mate with.