chapter 2: evidence for evolution and principles of darwinian evolution

Question 1

What is natural selection?

Answer 1

=> Mechanism for evolutionary change
=> Results in adaptive evolution
=> Natural selection acts on individuals but changes populations over time
=> Individuals possessing certain heritable traits leave more offspring than others

Question 2

What is the first part of natural selection?

Answer 2

1) Overproduction of offspring:
- Species are capable of producing more offspring than the environment can support

Question 3

What is the second part of natural selection?

Answer 3

2) Availability of resources/competition:
- Environmental resources are limited
- Organisms compete for limited resources (ex. food, water, light, space)
- Organisms die because of predators, disease, unfavorable environmental conditions

Question 4

What is the third part of natural selection?

Answer 4

3) Variation in population:
- Populations become genetically diverse and individuals have different characteristics
- In order for natural selection to work, VARIATIONS that are selected for must be HERITABLE (ex. not muscle mass or dyed hair color)

Question 5

What is the fourth part of natural selection?

Answer 5

4) Differential reproductive success (selection => adaptation)
- Unequal ability of individuals to survive and reproduce (individuals with beneficial adaptations are more likely to survive to pass on their genes (survival of the fittest))
- Leads to a gradual change in a population, with favorable characteristics accumulating over generations (adaptation)

Question 6

What was the background knowledge Darwin used to develop his idea of natural selection?

Answer 6

• Fossil record
• Knowledge of geography (Hutton & Lyell)
• Artificial selection
• Population growth (Malthus)