3.6: Evolution of Species Flashcards
1
Q
What is a mutation?
A
A rare and random change to genetic material
2
Q
What are the 3 possible effects of a mutation?
A
- Neutral: no effect
- Positive: survival advantage gained
- Negative: disadvantage to others, less likely to survive
3
Q
What are the 2 environmental factors that can increase mutation rates?
A
- Radiation
- Chemicals
4
Q
Why is variation important?
A
Allows populations to evolve and adapt to changing environmental conditons
5
Q
What is an allele?
A
A different version of the same gene
6
Q
What is natural selection?
A
The process by which evolution occurs
7
Q
What are the steps of natural selection?
4
A
- Species produce more offspring than the environment can sustain
- The best adapted individuals in a population survive
- Survivors reproduce and pass on favourable alleles with the selective advantage
- Favourable alleles increase in frequency within population
8
Q
What is speciation?
A
The process of a new species evolving
9
Q
What happens in the process of speciation?
3
A
- Isolation: part of a population becomes isolated by an isolation barrier
- Mutation: over a long period of time different mutations will occur in each sub population
- Natural Selection: selection pressures lead to sub populations evolving until they are so genetically different that they became different species
10
Q
What are the 3 types of isolation barriers?
A
- Geographical (e.g: rivers)
- Ecological (e.g: different habitats)
- Behavioural (e.g: different mating behaviours)
11
Q
How are new species formed?
6
A
- Populations become isolated by an isolation barrier
- Mutations occur randomly in the sub-populations
- There are different selection pressures for each sub populations
- Natural selection selects advantageous mutations
- Sub populations become genetically different
- Can no longer interbreed to produce fertile offspring
