AQA · GCSE · Biology
Course version: 8461 · Version from Sept 2018
If the new phenotype is suited to an environmental change it can lead to a…
Full specification wording
Variation: If the new phenotype is suited to an environmental change it can lead to a relatively rapid change in the species.
When the environment changes, such as a shift to colder weather or a new predator, organisms with a phenotype suited to the new conditions are more likely to survive and reproduce.
Checked against the AQA 8461 specification (opens in a new tab) on .
- Point 6 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
When the environment changes, such as a shift to colder weather or a new predator, organisms with a phenotype suited to the new conditions are more likely to survive and reproduce. Their alleles are passed to offspring, so the beneficial allele becomes more common in the population over generations. Because selection acts on every generation, the change in the species can be relatively rapid, especially in organisms with short generation times such as bacteria or insects. A method is to write the sequence: environmental change, variation already present, some individuals better suited, these survive and reproduce, beneficial allele frequency rises, population changes. The new phenotype must already exist; the environment does not create it, it selects it.
What earns the marks
- An environmental change alters which phenotypes are best suited to survive.
- Individuals with the suited phenotype survive, reproduce and pass on the beneficial allele.
- The frequency of the beneficial allele increases in the population over generations.
- Because selection acts each generation, the change in the species can be relatively rapid.
- The rate of change is faster in organisms with short generation times, such as bacteria.
Common mistakes and how to put them right
Saying organisms mutate in order to suit the new environment.
Put it right by stating that variation already exists and selection acts on it.
Confusing a change in an individual with a change in the species.
Put it right by describing a change in allele frequency in the population over generations.
Claiming the change is always slow.
Put it right by explaining that strong selection and short generation times can make it relatively rapid.
Exam tips
- Structure answers as environmental change, selection, reproduction, allele frequency change.
- Use the phrase survival of the fittest only if you then explain what fittest means in the context.
- Refer to allele frequencies rising or falling in the population rather than saying the species decides to change.
Try the lesson
The start of the Variation: If the new phenotype is suited to an environmental change it can lead to a relatively rapid change in the species. lesson, made from checked teaching notes for this specification point.
Have a go first
A population of insects lives on trees where the bark has turned dark brown. A mutation produces some dark brown insects, while the rest are pale green. Birds eat the pale green insects more easily. What is most likely to happen to the number of dark brown insects over the next few generations?
Listen
When the environment changes, such as a shift to colder weather or a new predator, organisms with a phenotype suited to the new conditions are more likely to survive and reproduce. Their alleles are passed to offspring, so the beneficial allele becomes more common in the population over generations. Because selection acts on every generation, the change in the species can be relatively rapid, especially in organisms with short generation times such as bacteria or insects. A method is to write the sequence: environmental change, variation already present, some individuals better suited, these survive and reproduce, beneficial allele frequency rises, population changes. The new phenotype must already exist; the environment does not create it, it selects it. A strong answer earns marks for these points. An environmental change alters which phenotypes are best suited to survive. Individuals with the suited phenotype survive, reproduce and pass on the beneficial allele. The frequency of the beneficial allele increases in the population over generations. Because selection acts each generation, the change in the species can be relatively rapid. A common slip: Saying organisms mutate in order to suit the new environment. Instead, stating that variation already exists and selection acts on it. Exam tip: Structure answers as environmental change, selection, reproduction, allele frequency change.
See it
Put it in order
Put these steps in the order they happen.
- 1. Some individuals better suited
- 2. Variation already present
- 3. Environmental change
- 4. Population changes
- 5. Beneficial allele frequency rises
- 6. These survive and reproduce
Key words
Say what each word means before you turn the card.
Natural selection
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Environmental change
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Allele frequency in populations
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Generation time and rate of evolution
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See every definition
- Natural selection
- Selection acts on variation already present, so individuals with a suited phenotype survive and reproduce and pass on the beneficial allele.
- Environmental change
- A shift in conditions that alters which phenotypes are best suited to survive.
- Allele frequency in populations
- The frequency of the beneficial allele increases in the population over generations.
- Generation time and rate of evolution
- The change in the species can be relatively rapid because selection acts each generation, and the rate of change is faster in organisms with short generation times.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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