5.2 Natural selection

IB Syllabus Statements

Understandings:

Natural selection can only occur if there is variation among members of the same species.
Mutation, meiosis and sexual reproduction cause variation between individuals in a species.
Adaptations are characteristics that make an individual suited to its environment and way of life.
Species tend to produce more offspring than the environment can support.
Individuals that are better adapted tend to survive and produce more offspring while the less well adapted tend to die or produce fewer offspring.
Individuals that reproduce pass on characteristics to their offspring.
Natural selection increases the frequency of characteristics that make individuals better adapted and decreases the frequency of other characteristics leading to changes within the species.

Applications and skills:

What is the generally accepted mechanism for evolution?
Explain how the theory of evolution can be used to understand the development of antibiotic resistance in bacteria.
Why is variation among members of the same species necessary for natural selection to occur?
Outline how mutation, meiosis and sexual reproduction cause variation between individuals in a species.
Explain what adaptations are with respect to natural selection.
Why is the idea that ‘species tend to produce more offspring than the environment can support’ an important idea for understanding natural selection?
Explain what ‘survival of the fittest’ means in terms of offspring.
“Individuals that reproduce pass on characteristics to their offspring.” Why is this important when discussing natural selection?
Discuss natural selection in terms of frequency of characteristics and adaptations.
Explain the well-known example of changes in the beaks of finches on Daphne Major.
Although the term ‘Lamarckism’ is not required, explain why characteristics acquired during the lifetime of an individual are NOT heritable.