Evidence and Mechanisms of Evolution

Question 1

evolution (2)

Answer 1

• species have changed through time

- new forms have arisen from common ancestors

Question 2

what evidence is there that species have changed through time? (2)

Answer 2

• direct observation

- fossil records

Question 3

how have we directly observed that species have changed through time?

Answer 3

• coronavirus, moths, crop pests, finches, HIV, experimental evolution

Question 4

how has the fossil record shown us that species have changed through time?

Answer 4

• different floras and faunas in past geological periods

Question 5

what evidence is there that new forms are derived from common ancestors? (3)

Answer 5

• fossil record
• direct observation
• homology

Question 6

how has the fossil record shown us that new forms are derived from common ancestors?

Answer 6

• intermediate/transitional forms

Question 7

how has direct observation shown us that new forms are derived from common ancestors?

Answer 7

• california salamander ring species

Question 8

homology

Answer 8

• similarity that isn’t functionally necessary

Question 9

analogy

Answer 9

• similarity due to shared ways of life

Question 10

how has homology shown us that new forms are derived from common ancestors? (2)

Answer 10

• vestigial structures, embryological similarities, homologies in general (tetrapod limb, genetic code, vertebrae embryo development)
• universal genetic code is ultimate evidence, it links all life to common ancestor

Question 11

what are the proposed theories for the history of life? (3)

Answer 11

• evolution
• creationism
• transformism

Question 12

creationism (2)

Answer 12

• universe and living organisms originate from specific act of devine creation, rather than evolution
• evidence of evolution proves this theory wrong

Question 13

transformism (3)

Answer 13

• transformation of one species into another by descent over many generations
• example: giraffes needed/wanted food on higher trees so they stretched their necks over time
• the evidence that “new forms are derived from common ancestors” proves this theory is false

Question 14

what are Darwin’s 4 postulates of evolution by natural selection?

Answer 14

1. turnover
2. variability
3. heritability
4. differential reproductive succes

Question 15

Darwin’s 4 postulates of evolution by natural selection: Turnover

Answer 15

• multiple units must undergo death and reproduction

Question 16

Darwin’s 4 postulates of evolution by natural selection: Variability

Answer 16

• there must be variability among the units

Question 17

Darwin’s 4 postulates of evolution by natural selection: Heritability

Answer 17

• variation must be passed from parents to offspring

Question 18

Darwin’s 4 postulates of evolution by natural selection: Differential reproductive success

Answer 18

• some variants are more likely to survive and reproduce than others

Question 19

heritability (2)

Answer 19

• measures the fraction of phenotypic variation among individuals that is due to differences in their genes
• slope of regression = heritability and measures extent to which offspring resemble parents

Question 20

heritability slope = 1.0 (2)

Answer 20

• strong resemblance

- strong response to selection and evolution occurs

Question 21

heritability slope = 0 (2)

Answer 21

• no resemblance

- no response to selection and evolution cannot occur

Question 22

what does the action of natural selection depend on and where does it come from (2)

Answer 22

• existence of appropriate variants

- new variants arise through mutation, a process random to the direction of evolution

Question 23

what environmental conditions are individuals/populations adapted to in natural selection

Answer 23

• adapted to environmental conditions of their immediate past and not their future

Question 24

evolution by natural selection (2)

Answer 24

• adaptive evolution

- turnover, variability, heritability, and differential (non-random) survival/reproduction

Question 25

evolution by genetic drift (2)

Answer 25

- neutral/non-adaptive evolution | - turnover, variation, heritability, random survival/reproduction

Question 26

consequences of genetic drift (3)

Answer 26

- responsible for most evolution that occurs at a molecular level (neutral evolution) - may lead to non-adaptive evolution by reducing genetic variability of populations - cause loss of favourable alleles or fixation on unfavourable alleles

Question 27

conditions leading to genetic drift (3)

Answer 27

- chronically small population size - population bottle necks - founder events

Question 28

benefit of homology

Answer 28

- 'model' organisms can be used in biomedical research - results may be extrapolated to humans if biological/cellular/molecular basis of the phenomenon being studied are homologous

Question 29

what is the importance of drift in evolution (2)

Answer 29

- may be a creative force in evolution by allowing populations to fully explore "rugged" fitness landscapes - emergence of new species/diseases