Unit 4: The modern synthesis

Question 1

What is the modern synthesis ?

Answer 1

The idea that introduced the connection between the units of evolution (genes) with the mechanism of evolution (selection)

Question 2

What are the 4 main discoveries that led to the modern synthesis ?

Answer 2

1) Macro and micro mutations and genetics of populations
2) Mutational analysis
3) Taxonomy and population genetics
4) Paleontology

Question 3

What are micro mutations ?

Answer 3

The biometrics believed that evolution occurred via small change that happens gradually
- Graph shifts slightly to right
- Gentle shift over number of generations

Question 4

What are macro mutations ?

Answer 4

The mendelians believed that evolution was caused by a mutation with massive consequence and that we would see a big change very quickly
- Large phenotypic events
- Small number of individuals undergo advantageous change

Question 5

Give an example of mutational analysis

Answer 5

Eye colour in drosophila melanogaster (fruit fly)

Question 6

How does taxonomy and population link to the modern synthesis ?

Answer 6

Found that:
- Genotype not phenotype determines a species
- Natural populations are genetically variable
- Natural selection does occur in natural populations

Question 7

Does palaeontology support or dismiss the theory of evolution ?

Answer 7

• It shows that morphology does change
• It shows that these changes may be gradual over a long time
  BUT
• It also shows change may happen rapidly over few generations

Question 8

What are the 4 ‘rules’ of modern synthesis ?

Answer 8

1) Genetic variation in populations arises by chance through mutation, gene segregation and recombination
2) Evolution consists of changes in the frequency of alleles between one generation and another due to genetic drift and gene flow
3) Most genetic changes have individually slight phenotypic effect
4) Diversification comes about by speciation

Question 9

What are the 3 differences between Darwin and the modern synthesis (MS) ?

Answer 9

1) MS recognises several mechanisms of evolution in addition to natural selection
2) MS recognises that characteristics are inherited as discrete entities called genes. Variation within a population is due to presence of multiple alleles of a gene
3) It postulates that speciation is due to the gradual accumulation of small genetic changes