Natural Selection

Question 1

What is an adaptation?

Answer 1

A characteristic that enhances survival or reproduction

Question 2

What makes a characteristic an adaptation vs just a characteristic?

Answer 2

Well suited for that particular environment

Question 3

How do adaptations cause a population to evolve?

Answer 3

The population becomes better suited to its habitat over many generations

Question 4

How is pseudocopulation inbee orchids an adaptation?

Answer 4

Looking like female bees and producing pheromones increases the pollination rate of the flowers. Is an adaptation only for reproduction and less so for survival

Question 5

Are all organisms equally well adapted?

Answer 5

No, different organisms show different levels of adaptation

Question 6

What is the difference between natural selection and artificial selection?

Answer 6

With natural selection, environmental pressures create selection pressure. With artificial selection, human intervention creates selection pressure

Question 7

How did cabbage, cauliflower, kohlrabi, kale, brussel sprouts, and broccoli arise from wild mustard?

Answer 7

Artificial selection for particular traits in wild mustard

Question 8

What is natural selection? 3 definitions

Answer 8

1. Differential survival and reproductive success among individuals due to selection pressures from the environment
2. Mechanism that allows individuals to respond to their environment by refining adaptations
3. Mechanism through which evolution occurs

Question 9

How does natural selection create differential reproductive success?

Answer 9

Individuals with favourable traits will be more likely to survive and reproduce than individuals with unfavourable traits, leading to an accumulation of that favourable trait in the population

Question 10

What is fitness?

Answer 10

Average lifetime contribution of individuals of a genotype to the populations after 1 or more generations

Question 11

What determines fitness for an asexually reproducing species?

Answer 11

Population growth

Question 12

What determines fitness for a sexually reproducing species?

Answer 12

1. Probability of surviving to reproductive maturity
2. Average number of offspring produced by the female
3. Average number of offspring produced by the male

Question 13

What happens when one genotype is more fit than another in terms of population growth and the next generation?

Answer 13

The fitter genotype has higher reproductive success. It grows faster so makes up more of the next generation

Question 14

What did John Endler’s experiments with the guppies show?

Answer 14

Natural selection may consist of differences in reproductive rate instead of survival

Question 15

When a feature is subject to conflicting selection pressures, which one determines the direction of evolution?

Answer 15

Whichever one is stronger

Question 16

What is required of a trait to be acted on by natural selection?

Answer 16

It must be heritable

Question 17

What sort of traits are not subjected to natural selection?

Answer 17

Characteristics acquired during the lifetime of the organism, since they aren’t heritable

Question 18

Is natural selection random?

Answer 18

No, it occurs in response to environmental pressures and results in adaptations that are beneficial for that environment

Question 19

Why can’t natural selection fashion perfect organisms?

Answer 19

It is limited by historical constraints and can only edit what is already present

Question 20

Why are adaptations often compromises?

Answer 20

Conflicting selection pressures

Question 21

What 3 things lead to natural selection?

Answer 21

• Variation - in the environment and between individuals
• Differential reproduction
• Heredity

Question 22

What are the 3 basic modes of selection?

Answer 22

Directional, disruptive, stabilizing

Question 23

What is directional selection?

Answer 23

One extreme is favoured over the other

Question 24

What happens to the population profile that is undergoing directional selection?

Answer 24

It moves in one direction to that extreme being selected for

Question 25

What is stabilizing selection?

Answer 25

Intermediate phenotypes are selected for over both extremes

Question 26

What is disruptive selection?

Answer 26

Both extremes are selected for over the intermediate phenotypes

Question 27

What can disruptive selection ultimately lead to?

Answer 27

Speciation

Question 28

What is the fitness of a genotype in asexually reproducing species?

Answer 28

Proportion surviving x average fecundity

Question 29

What is the absolute fitness of a genotype for an asexually reproducing species?

Answer 29

Per capita growth rate of that genotype

Question 30

What is the relative fitness of a genotype for an asexually reproducing species?

Answer 30

Comparison between the R values of the genotype of interest and a reference genotype with the highest R value

Question 31

What is the absolute fitness for a sexually reproducing species?

Answer 31

Number of zygotes produced over a lifetime = probability that an individual survives to reproductive maturity x the expected number of offspring

Question 32

What are 4 components of selection that affect allele frequencies?

Answer 32

1. Viability
2. Mating success
3. Fecundity
4. Fertilization success

Question 33

What is viability?

Answer 33

The probability that an individual survives to reproductive maturity

Question 34

What is mating success?

Answer 34

The number of mates obtained by an individual

Question 35

What is fecundity?

Answer 35

Average number of viable offspring per female