Human Evolution Exam 1 Study Guide – Revision Notes & Key
Concepts
Natural Selection: - ANS ✔✔1. All species are capable of producing offspring at a faster rate
than food supplies increase
2. Because in each generation more individuals are produced than can survive, there is a
competition for limited resources
1. There is biological variation in all species
2. Some individuals in the population will possess traits that allow them to survive and
reproduce more successfully than others in the same environment
3. Environmental conditions determine whether a trait is beneficial
4. Traits are inherited and passed on to the next generation. Individuals who possess favorable
traits contribute more offspring to the next generation than do others, so these traits become
more common. Those individuals that produce more offspring have greater reproductive
success.
5. Over long periods of time, favorable traits accumulate in a population so that later
generations are distinct from ancestral ones. In time, a new species appears
6. Geographic isolation may also lead to the formation of a new species
• Natural selection causes evolutionary change
• Evolution is the change in the genetic structure of a population over time
- Changes in allele frequencies due to differential reproductive success
- Systematic (not random)
- Increases variation between populations
- Decreases variation within populations
, Three types of natural selection: - ANS ✔✔- Directional selection
- Stabilizing selection
- Disruptive selection
Unit of natural selection: - ANS ✔✔- Is the individual
- Counter Lamarck
Unit of evolution: - ANS ✔✔- the population
Gene Flow: - ANS ✔✔- use of codons to make certain proteins
- some proteins can be created by several different nucleotide makeups, codons
- redundancy helps protect against a mutation / mistake
- we only need 20 amino acids, so we don't need a more complex system than three base
codons / triplet codons
• The exchange of alleles between populations
• Migration
• Systematic
• Increases variation within populations
• Decreases variation between populations
Genetic Drift: - ANS ✔✔- Change in allele frequencies produced by random factors
- Increases variation between populations
- It is unlikely every population will be fixed on the same allele (the other allele could go into
fixation in other populations by random chance)
- Decreases variation within populations (one allele will eventually disappear because
eventually an entire population is fixed on a certain type of allele)
Concepts
Natural Selection: - ANS ✔✔1. All species are capable of producing offspring at a faster rate
than food supplies increase
2. Because in each generation more individuals are produced than can survive, there is a
competition for limited resources
1. There is biological variation in all species
2. Some individuals in the population will possess traits that allow them to survive and
reproduce more successfully than others in the same environment
3. Environmental conditions determine whether a trait is beneficial
4. Traits are inherited and passed on to the next generation. Individuals who possess favorable
traits contribute more offspring to the next generation than do others, so these traits become
more common. Those individuals that produce more offspring have greater reproductive
success.
5. Over long periods of time, favorable traits accumulate in a population so that later
generations are distinct from ancestral ones. In time, a new species appears
6. Geographic isolation may also lead to the formation of a new species
• Natural selection causes evolutionary change
• Evolution is the change in the genetic structure of a population over time
- Changes in allele frequencies due to differential reproductive success
- Systematic (not random)
- Increases variation between populations
- Decreases variation within populations
, Three types of natural selection: - ANS ✔✔- Directional selection
- Stabilizing selection
- Disruptive selection
Unit of natural selection: - ANS ✔✔- Is the individual
- Counter Lamarck
Unit of evolution: - ANS ✔✔- the population
Gene Flow: - ANS ✔✔- use of codons to make certain proteins
- some proteins can be created by several different nucleotide makeups, codons
- redundancy helps protect against a mutation / mistake
- we only need 20 amino acids, so we don't need a more complex system than three base
codons / triplet codons
• The exchange of alleles between populations
• Migration
• Systematic
• Increases variation within populations
• Decreases variation between populations
Genetic Drift: - ANS ✔✔- Change in allele frequencies produced by random factors
- Increases variation between populations
- It is unlikely every population will be fixed on the same allele (the other allele could go into
fixation in other populations by random chance)
- Decreases variation within populations (one allele will eventually disappear because
eventually an entire population is fixed on a certain type of allele)
