Fastest growth comes before the biggest population
- The idea
- Predict
- See it
- Why
- Check
The idea
“A population is at its biggest when it's growing fastest.”
The steepest part of a growth curve looks like the big moment, so it's easy to call it the top. Slower growth is still growth, and the curve keeps climbing.
The short version
The mistake: A population is at its biggest when it's growing fastest.
What's actually true: A population keeps getting bigger as long as births outnumber deaths, so it peaks after its fastest growth.
- Size is how many there are. Growth rate is how many are added per day. A population grows whenever births outnumber deaths, even by a little.
- In logistic growth, the number added per day peaks at half the carrying capacity. The carrying capacity is the most individuals the environment can support.
- Past that point, crowding narrows the gap between births and deaths, so growth slows. The population rises until births and deaths even out at the carrying capacity.
On the exam: The biggest population comes when births and deaths even out. The fastest growth comes earlier.