Variation
Introduced| English | Meaning |
|---|---|
| variation/ˌveərɪˈeɪʃn/ | Differences in characteristics between individuals or values within a set. |
| continuous/kənˈtɪnjuːəs/ | Changing without a break or jump, or taking every value within an interval. |
| discontinuous/dɪskənˈtɪnjuːəs/ | discontinuous |
| mutations/mjuːˈteɪʃnz/ | A change in genetic material, such as a DNA sequence or chromosome structure. |
No two alike
- Look around a classroom: everyone is different. Even the same species shows differences.
- These differences are variation 变异, and they come from genes and the environment.
Variation lab
Classify examples of variation by pattern and cause.
Which is an example of genetic variation?
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Blood group is determined by genes; the others are environmental.
Genetic and environmental variation
- Genetic variation comes from your genes (e.g. eye colour, blood group).
- Environmental variation comes from your surroundings (e.g. a scar, a language you speak).
- Most variation is a mix of both (e.g. height).
Continuous 连续的 variation is a smooth range; discontinuous 不连续的 variation falls into separate groups
Which shows continuous variation?
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Height varies over a continuous range.
Continuous and discontinuous
- Continuous variation: a range of values (height, mass) — shown on a graph as a smooth curve.
- Discontinuous variation: distinct categories (blood group, tongue rolling).
The dark (melanic) form of the peppered moth — the form favoured on soot-darkened bark
Which create genetic variation? (Select all that apply.)
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Meiosis, fertilisation and mutations create variation; diet is environmental.
Variation is the raw material that natural selection acts on.
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Without variation there could be no natural selection.
A random change to DNA that can create a new allele is a ______.
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Mutations are the source of new alleles.
Where genetic variation comes from
- Meiosis and fertilisation mix alleles, creating new combinations.
- Mutations 突变 (random changes to DNA) create brand-new alleles.
Variation is the raw material for evolution. Without differences between individuals, natural selection would have nothing to act on. Variation makes adaptation possible.
You've got it
- variation comes from genes, the environment, or both
- continuous = a range (height); discontinuous = categories (blood group)
- genetic variation comes from meiosis, fertilisation and mutations