Gradualism, Punctuated Equilibrium & Natural Section

Question 1

What does gradualism suggest?

Answer 1

• that species evolve gradually by small changes over long periods of time

Question 2

What does punctuated equilibrium refer to?

Answer 2

• the speed at which evolution takes place
• not gradual

Question 3

What were the 4 observations Darwin made that led him to formulate his theory about the mechanism of evolution?

Answer 3

1. more offspring are produced than are required
2. natural variation
3. a change in the environment leads to differential reproductions
4. characteristics (traits) were heritable

Question 4

What is differential reproduction or ‘survival of the fittest’?

Answer 4

• when better adapted individuals survive to reproduce while the less adapted most likely die or fail to reproduce

Question 5

How does natural selection operate?

Answer 5

• it only operates on variation in inherited characteristics
• (if all individuals of a population were genetically identical, there would be no natural selection)

Question 6

What is natural selection?

Answer 6

• a process by which nature selects for survival those individuals that are best adapted to environmental conditions and, as a result, will produce the most offspring

Question 7

What does natural selection provide?

Answer 7

• a mechanism for evolution
• which can adapt species to the environment and ultimately may lead to the origin of a new species

Question 8

Is natural selection a random process?

Answer 8

• no
• the organisms that are selected for survival are those that are better adapted to the environment

Question 9

What causes genetic variation?

Answer 9

• germ-line point mutations
• duplication of genes or swapping their positions within chromosomes
• the deletion or duplication of whole chromosomes
• sexual reproduction

Question 10

Why do offspring differ from their parents?

Answer 10

• genetic variation
• effect of environmental factors

Question 11

Why are only some offspring selected for survival?

Answer 11

• selective forces will favour some phenotypes more than others
• which results in differential reproduction

Question 12

What are some examples of selective forces that influence survival?

Answer 12

• competition
• predation
• climatic factors
• disease
• parasitism

Question 13

What is the result of natural selection?

Answer 13

• a new favourable genotype thus becomes more frequent in the population
• possibly forming a new species