Preview - From Ecosystems To Speciation

Introduction


Competition Between Populations

Purpose

How do populations affect each other in ecosystems?

Model Rules

In this model, a population of bugs are able to wander the world, eating grass as they go.  As the bugs eat grass, they gain energy, and as they move they lose energy.  If they run out of energy, the bugs will die, and if they gain enough energy, they will reproduce.

In this scenario, you will investigate how the bug population behaves with no outside influences.

Set the region % grassland to 100 in and the initial-birds to zero in both ecosystems before you begin.

 


Questions

Please answer the questions below.

What unit of time do you think a tick might represent in this model?

1 second
1 minute
1 hour
1 day
1 week
1 month
1 year

How long (number of ticks) does it take for the bug population to reach a stable size? What is going on in the model that makes you believe the population is stable?


This stable size is called a carrying capacity. Please provide a rough estimate of the carrying capacity of the bug population in this situation. (try moving your cursor over the graph) 


In this environment, there are always some bugs dying and some bugs reproducing.  However, the model shows us that after the bug population stabilizes, it stays mostly constant.  What does this suggest about the average death rate and average birth rate of the bugs after the population stabilizes?  How do they compare?


When the bug population is low, why does it increase to the carrying capacity?  It will be helpful to think about what factors might affect the birth and death rates of the bugs.


When the bug population is high, why does it decrease to the carrying capacity?  Again, it will be helpful to think about what factors might affect the birth and death rates of the bugs.


How do you think the carrying capacity of the bug population will change when predators (birds) are added to the ecosystem?

It will increase
It will stay roughly the same
It will decrease

Notes

These notes will appear on every page in this lesson so feel free to put anything here you'd like to keep track of.