Back to: ZOOLOGY 100 Level
I’m so excited to see you again, ready to learn something new and exciting! You are truly doing amazing things. Today, we are going to learn about population growth models. Don’t worry — it sounds big, but by the end of this lesson, you’ll see it’s as simple as understanding how a group of goats in a village multiplies over time. Let’s go!
Population growth models
What is Population Growth?
Population growth simply means the increase in the number of individuals in a group over time.
Just imagine if two rabbits in your compound have babies, and those babies grow up and have their own babies — soon, your compound will be full of rabbits! That’s population growth.
Types of Population Growth Models
- Exponential Growth Model
This type of growth happens when there are plenty of resources like food, water, and space, and nothing is stopping the population from increasing.
- The population keeps multiplying very fast, like when rice keeps boiling over because the fire is too high.
- The graph of exponential growth looks like a “J” shape — it rises slowly at first, then very fast!
Example:
If a farmer starts with two chickens and they have chicks, and those chicks also grow and have more chicks without any sickness or hunger, the number of chickens will keep rising rapidly.
Key Point:
Exponential growth happens in perfect conditions — but in real life, perfect conditions hardly last long.
- Logistic Growth Model
This model is more realistic because it considers that resources (like food, water, and space) are limited.
- In logistic growth, the population first grows fast (like exponential), but later it slows down when there are not enough resources to support everyone.
- The graph looks like an “S” shape — it goes up, then levels off.
Example:
Imagine a fish pond. At first, few fishes have plenty of food and space, so they multiply fast. But after a while, too many fishes means not enough food, and the growth slows down.
Key Point:
Logistic growth happens in real life because no environment has unlimited resources.
Important Terms to Know
- Carrying capacity: The maximum number of individuals that the environment can support without problems.
- Limiting factors: Things like lack of food, diseases, predators, or bad weather that slow down population growth.
Summary
- Population growth means the increase in the number of individuals over time.
- Exponential growth is fast and unlimited (J-shaped curve).
- Logistic growth starts fast but slows down when resources become limited (S-shaped curve).
- Carrying capacity is the maximum number of individuals an environment can support.
Evaluation
- What is population growth?
- Explain exponential growth with an example.
- What makes logistic growth different from exponential growth?
- What does carrying capacity mean?
- Why does population growth slow down in the logistic model?
I am so proud of you for taking your learning seriously. Always remember: you are smart, capable, and destined for greatness! Stay with Afrilearn, and the sky will be your starting point. Let’s keep going!