Extinction: no surviving individuals
| English | Français |
|---|---|
| extinction/ekˈstɪŋkʃn/ | extinction |
| competitor/kəmˈpetɪtə/ | concurrent |
What would explain this observation?
- A species missing from one pond may still survive elsewhere. Extinction 灭绝 refers to the whole species, not just one sampling location.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- Extinction occurs when no individuals of a species remain alive. Environmental changes can make resources or conditions unsuitable. New predators, diseases or competitors 竞争者 can reduce survival and reproduction. Catastrophic events can remove populations rapidly. Several pressures may interact, so an explanation should use the evidence in the particular scenario.
- extinction: Loss of a species with no individuals remaining alive; competitor: An organism competing for a limiting resource.
Which observation directly fits extinction?
A small, fragmented population may be vulnerable to loss even when some individuals survive a disturbance. If mortality exceeds successful reproduction for long enough, the number can reach zero. A local disappearance is not global extinction unless the evidence shows no surviving population elsewhere. An unsuccessful survey alone does not establish that conclusion.
Match each technical term to its precise meaning.
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- A small, fragmented population may be vulnerable to loss even when some individuals survive a disturbance. If mortality exceeds successful reproduction for long enough, the number can reach zero. A local disappearance is not global extinction unless the evidence shows no surviving population elsewhere. An unsuccessful survey alone does not establish that conclusion.
- Read supplied population records with births, deaths and migration stated. Identify mechanisms, calculate net change and separate observations from proposed causes. Consider detection limits and unsurveyed habitats. Conservation discussion should examine feasible actions and uncertainty rather than asserting that every decline has one cause.
Which two habits make the investigation or model in this case more defensible?
Read supplied population records with births, deaths and migration stated. Identify mechanisms, calculate net change and separate observations from proposed causes. Consider detection limits and unsurveyed habitats. Conservation discussion should examine feasible actions and uncertainty rather than asserting that every decline has one cause.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a closed fictional population starts with 30 individuals, has 8 surviving births and 14 deaths during one interval. Final count = 30+8−14 = 24. The decline is 6/30×100 = 20%. A decline does not yet equal extinction, and repeating this arithmetic assumes unchanged rates that the evidence may not support.
A closed model population starts at 45 with 9 surviving births and 16 deaths. Find the final count. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A closed model population starts at 45 with 9 surviving births and 16 deaths. Find the final count.
The result is 38 individuals. Known: a closed fictional population starts with 30 individuals, has 8 surviving births and 14 deaths during one interval. Final count = 30+8−14 = 24. The decline is 6/30×100 = 20%. A decline does not yet equal extinction, and repeating this arithmetic assumes unchanged rates that the evidence may not support.
Check the conclusion and its limits
- Extinction is not one individual dying or a species moving away from one site. A low population count is a warning, not a claim of zero. Evolutionary adaptation cannot be assumed to rescue every population quickly enough.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
A declining population is already extinct. This claim is false: Extinction is not one individual dying or a species moving away from one site. A low population count is a warning, not a claim of zero. Evolutionary adaptation cannot be assumed to rescue every population quickly enough.
Extinction: no surviving individuals: A small, fragmented population may be vulnerable to loss even when some individuals survive a disturbance. If mortality exceeds successful reproduction for long enough, the number can reach zero. A local disappearance is not global extinction unless the evidence shows no surviving population elsewhere. An unsuccessful survey alone does not establish that conclusion.
A declining population is already extinct.
Extinction is not one individual dying or a species moving away from one site. A low population count is a warning, not a claim of zero. Evolutionary adaptation cannot be assumed to rescue every population quickly enough.
Loss of a species with no individuals remaining alive: write the technical term.
extinction means Loss of a species with no individuals remaining alive.