Natural selection — Science definition
Defined in 2 courses:
- The process by which variants leaving more surviving offspring become more common; it needs heritable variation, differential reproduction and inheritance, and nothing else. (Life Science & Scientific Inquiry)
- The process by which individuals whose heritable traits are better suited to their environment tend to survive and reproduce at higher rates, so those traits become more common in the population over generations. (Life Science: Biology)
Where it is taught
- Natural Selection, Adaptation & Population Change — Evolution, Evidence & Life History, Life Science & Scientific Inquiry, Grade 7
- Natural Selection — Evolution, Ancestry & Biodiversity, Life Science: Biology, Grade 10
In use
That is natural selection observed directly, in the wild, with numbers.
Natural Selection, Adaptation & Population Change
That mechanism is natural selection, and its real power is that it needs no designer and no goal.
Natural Selection
Questions using natural selection
Problem 1
Answer and explanation
No. It can be an individual developmental response. Selection requires inherited variation and differing reproductive contribution across generations.
Response criteria
- Explain the relevant biological process accurately.
- Use the supplied evidence and show calculation steps with units where needed.
- Connect a labeled model or mechanism with the claim.
- State an assumption, evidence limitation, or useful next observation.
Problem 2
- An organism's conscious effort to change
- The environment directly rewriting an organism's genes as needed
- Mutation (with reshuffling of genes in sexual reproduction)
- Traits organisms build up through exercise and practice
Answer and explanation
Mutation (with reshuffling of genes in sexual reproduction)
New alleles arise from random mutation; sexual reproduction then reshuffles this variation. Natural selection can only act on variation that already exists.
Problem 3
Answer and explanation
(1) Heritable variation: individuals differ in traits that can be passed to offspring. (2) Overproduction: populations make more offspring than can survive. (3) Competition: individuals compete for limited resources. (4) Differential survival and reproduction: individuals with traits better suited to the environment survive and reproduce more, so those traits become more common over generations.
Problem 4
- variation that arises in response to need
- heritable variation already present in a population
- individuals that choose to change
- acquired skills
Answer and explanation
heritable variation already present in a population
Selection can only favour or disfavour variation that already exists and is heritable; it does not generate variation on demand.