Population Ecology
Introduced| English |
|---|
| exponential growth/ˌekspəˈnenʃl ɡrəʊθ/ |
| carrying capacity/ˈkæriɪŋ kəˈpæsɪti/ |
| logistic growth/ləˈdʒɪstɪk ɡrəʊθ/ |
How populations grow
- A single pair of rabbits can become a huge population in a few years.
- But no population grows without limit forever.
- Something always slows it down.
- Population ecology studies how and why numbers rise and level off.
Exponential growth
- With plenty of food and space, a population grows faster and faster.
- This is exponential growth 指数增长 — a J-shaped curve.
- Each generation adds more individuals than the last.
- But this cannot continue for long in the real world.
When resources are unlimited, a population shows exponential growth, which means it…
Exponential growth speeds up as the population gets bigger — a J-shaped curve.
Carrying capacity
- Every environment can support only so many individuals.
- That limit is the carrying capacity 承载力, written K.
- As the population nears K, food, water, and space run short.
- Growth slows, then stops, holding near this ceiling.
How a population grows
logistic growth to capacity K
Growth is exponential at first, then levels off at the carrying capacity as resources run low.
The carrying capacity of an environment is…
The carrying capacity (K) is the maximum population an environment can sustain with its resources.
Logistic growth
- Real populations usually follow logistic growth 逻辑斯谛增长.
- It starts exponential, then flattens near the carrying capacity — an S-shaped curve.
- Below K the population grows; near K it holds steady.
- The result is a stable population balanced with its resources.
Logistic growth starts fast, then levels off at the carrying capacity — an S-shaped curve.
Logistic growth is exponential at first, then flattens as resources run low near carrying capacity.
Population growth slows as a limited resource, like food or ____, runs out.
Limited food, water, and space slow growth as the population nears carrying capacity.
Select all true statements about population growth.
No population grows exponentially forever — resources always run out. The other three are correct.
Exponential growth cannot last. It looks unstoppable, but every real environment has limits. Sooner or later food, space, or another resource runs out, and growth slows toward the carrying capacity. A J-curve always bends into an S-curve in the end.
Bacteria in a flask:
- Add a few bacteria to fresh nutrients and they multiply exponentially.
- Soon the nutrients run low and waste builds up.
- Growth slows and the population levels off — logistic growth, limited by carrying capacity.
Populations grow fast at first — exponential growth — but no environment can support unlimited numbers. Its carrying capacity (K) is the sustainable maximum. Real populations follow logistic growth: exponential at first, then levelling off at K as resources like food and space run low.