Midterm Study Cards

Question 1

Darwin’s theory of evolution by natural selection attempts to explain two big patterns. What are those patterns and what lines of evidence support the process of evolution?

Answer 1

-groups that live closer together are more alike
-species are related through common ancestry
Evidence:
Fossils show a record of a change overtime (carbon dating), extinction - prove that things change and evolve, Homologous traits, genetics

Question 2

What criteria need to be met for natural selection to operate on a population?

Answer 2

(Darwin’s 4 postulates)
Variation in the trait, that variation in the trait is heritable, heritable variation is linked to reproductive success

Question 3

In what ways can natural selection be constrained?

Answer 3

fitness trade offs
-selection acts on variation that exists
-plyotophy ?

Question 4

What can natural selection do that no other evolutionary process can?

Answer 4

Only selection that leads to adaptation

Question 5

What is the Hardy-Weinberg principle and why is it useful?

Answer 5

No evolution - it’s a series of assumptions on the conditions where evolution does not occur
Why is it useful?
If an assumption is violated then it tells us that there is evolution occurring

Question 6

What are you comparing when you apply the Hardy-Weinberg principle? What do you need to calculate to make the necessary comparison?

Answer 6

Comparing the genotype frequencies to the observed and expected frequencies

Question 7

What are the different modes of natural selection and what are their effects on genetic diversity?

Answer 7

Disruptive selection - favours the act of the disruption (increase/maintain diversity)
Directional selection- shifts one direction (Increase genetic diversity)
Stabilizing selection - stays in the middle (decrease genetic variation)
Balancing selection - maintains genetic variation for the environment *

Question 8

Small populations are often at greater risk of extinction. What is one factor discussed in the course that could contribute to this?

Answer 8

Inbreeding (reduces genetic diversity, decreases fitness, deleterious recessive alleles (bad allele), increases homozygosity and decreases heterozygosity

Question 9

Small populations are often at greater risk of extinction. What is one factor discussed in the course that could contribute to this?

Answer 9

Inbreeding (reduces genetic diversity, decreases fitness, deleterious recessive alleles (bad allele), increases homozygosity and decreases heterozygosity

Question 10

Why does sexual selection usually act more strongly on males than females? If you were asked this question as an essay, what would you need to discuss/explain to fully answer the question?

Answer 10

Male competition/fitness, males have greater reproductive chance

Question 11

What are the four species concepts that we covered? What criteria does each concept use to delimit species? What are some advantages and disadvantages of each?

Answer 11

Biological species - Group of breeding individuals
Morphological -
Ecological species - function in the environment
Phylogenetic species - homologous traits, monophyletic groups within

Question 12

Is reproductive isolation essential for the formation of species?

Answer 12

Yes, very important

Question 13

Hardy-Weinberg formula

Answer 13

P2+2pq+q2=1

Question 14

Why doesn’t inbreeding depression, by itself, cause evolution?
a) It decreases the population’s average fitness
b) It limits gene flow
c) It does not change the population’s allele frequencies
d) It increases Homozygosity
e) It violates the Hardy-Weinberg assumptions

Answer 14

e) It violates the Hardy-Weinberg assumptions

Question 15

In seedcracker finches from cameroon, small- and large-billed birds specialize inn cracking soft and hard seeds, respectively. If long-term climatic change resulted in all seeds becoming hard, what type of selection would then operate on the finch population?

a) disruptive selection
b) directional selection
c) stabalizing selection
d) no selection would operate because the population is in Hardy-Weinberg equilibrium

Answer 15

b) directional selection

Question 16

Which of the following is most likely to produce an African butterfly species in the wild whose populations show two strikingly different color patterns?
a) artificial selection
b) directional selection
c) stabilizing selection
d) disruptive selection
e) sexual selection

Answer 16

d) Disruptive selection

Question 17

Which of the following reproductive barriers would prevent a mating attempt?
a) behavioural isolation
b) hybrid sterility
c) gametic isolation
d) sexual selection

Answer 17

a) behavioural isolation

Question 18

Which of the following statements is true?
a) Natural selection is the only mechanism of evolutionary change
b) Individuals evolve, becoming better adapted to their environment
c) The fittest individual is always the one that survives the longest
d) Both survival and reproductive ability contribute to an organism’s fitness.

Answer 18

d) Both survival and reproductive ability contribute to an organism’s fitness

Question 19

The following concepts of evolutionary theory are due to random events (i.e., chance) EXCEPT
a) mutation
b) the bottleneck effect
c) natural selection
d) genetic drift

Answer 19

b) the bottleneck effect

Question 20

Similar gill pouches in embryos of a chick, human, and cat are an example of _______

Answer 20

The inheritance of acquired characters

Question 21

Fill in the blank

A (….) is a big molecule of DNA made up of small repeating units

Answer 21

Chromosome