How do Environmental Changes affect a Population?
Online Lab
Name:
Date:
Open up the website http://www.campbellbiology.com Select the orange edged book, and enter
milliga9@msu.edu as the login name and pearly31 as the password. From the pull down menu select
Chapter 1: Exploring Life (probably already showing). Under the section Concept 1.4, Investigation:
How do Environmental Changes affect a Population?
Read the information that is in the upper right quadrant of the screen and follow its directions. You
will be able to type in data directly in the Lab Notebook and answer the Question in the boxes given,
but make sure you enter all information on this sheet to keep in your binder. (The lab notebook is at
the end of the questions.)
Lab Report – These are the questions you are asked to answer as you go through the lab. Your lab notebook begins
after the questions (page 3).
1. What role does genetics play in the variation seen in this leafhopper population?
We see variation in the size (small, medium and large) and body color (black and brown) of the leafhoppers.
These are two traits that are controlled by genes. The environment can favor one trait over the others,
which would lead us in to natural selection.
2. Note the results from the 20th generation under global warming conditions. Before continuing with the 30th
generation, predict the population composition of the 30th generation.
Possible prediction: All or almost all of the leafhoppers will be small.
3. What happened to the proportion of each type of leafhopper in subsequent generations under global warming
conditions? Suggest a reason why the traits of the 30th generation make this population better adapted to its
altered environment.
-The size of the leafhoppers decreased over the 30 generations.
- Smaller body size may be an advantage in warmer temperatures since they may require less food and a
small body size helps them to regulate body temperature more easily (stay cooler easier)
4. Why would you expect a change in predators to cause a difference in the types of leafhoppers being selected?
A new predator may prefer a different color of leafhopper (they may see colors differently). Size can
affect how much (or how little) a predator must eat to be satisfied.
5. Note the differences between the parental, 10th and 20th generations when the predator changed from a bird
to a snake. What evidence supports the view that leafhopper size is not affected by a change in predators?
In the later generations we see relatively the same number of large and small leafhoppers. Since their
numbers remain the same, we know the change in predators hasn’t affected the size of the population.
We could also phrase it this way: A change in predators did not affect the size of leafhoppers seen after the
20th generation.
6. What happened to the proportion of each type of leafhopper in subsequent generations when the predator
changed from a bird to a snake? Suggest a reason why the traits predominant in the 30th generation make this
population better adapted to the change in predators.
The number of black leafhoppers descreased. It is possible that the snake can not see the brown
leafhoppers as well as the black leafhopper and therefore don’t eat them as often.
7. Describe some human activities around your school that could have influenced the natural vegetation in the area.
Human activities that can influence the type of vegetation include building homes and using pesticide.
Building new homes would destroy naturally occurring vegetation (trees, bushes, other plants). Homeowners
often use pesticides (or herbicides) to get rid of unwanted “weed” vegetation.
8. Note the differences between the parental and the 30th generations. What happened to the proportion of each
type of leafhopper when the vegetation changed? Suggest a reason why the traits of the 30th generation make
this population better adapted to its altered environment.
When the vegetation changes, both the size and color of the leafhoppers was affected. Over time, our
leafhopper population changed to medium body size and black body color.
9. Identify some major sources of pesticides in your area.
Homeowners, factories, government
10. What happened to the proportions of leafhoppers in each subsequent generation when pesticides were added
to the environment? Explain why all the leafhoppers were not killed by the pesticide application.
When pesticides were added to the environment, the leafhoppers average size increased and the color
was predominantly black. It is possible that some of the leafhoppers had a gene that made them
resistant to pesticides. It they had the gene, they would survive the environment change and then
pass that gene on to their offspring.
Lab Notebook
Global Warming Data Table – possible data
Number of:
Parental
Generation
10th Generation
20
th
Generation
30
th
Generation
Large
Size
Medium
Small
Black
Color
Brown
2
22
1
22
3
0
0
0
20
10
3
5
15
22
25
25
25
0
0
0
Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE SIZE DATA! Include a title,
key, and labels!
Number of Leafhoppers
Change in leafhopper body size with an increase in
temperature over 30 generations.
Generation
Predator Change Data Table
Number of:
Parental
Generation
10th Generation
20th Generation
30th Generation
Graph on next page
Large
Size
Medium
Small
Black
Color
Brown
1
22
2
22
3
1
1
0
23
23
25
1
1
0
15
10
2
10
15
23
Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE COLOR DATA! Include a title,
key, and labels!
Number of Leafhoppers
Change in leafhopper body size with an increase in
temperature over 30 generations.
Generation
Vegetation Change Data Table
Large
Size
Medium
Small
Black
Brown
Parental
Generation
10th Generation
2
22
1
22
3
1
23
1
23
2
20th Generation
0
25
0
24
1
0
25
0
25
0
Number of:
30
th
Generation
Color
Number of Leafhoppers
Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE COLOR DATA! Include a title,
and labels!
Change in leafhopper body size with an increase in
temperature over 30 generations.
Generation
key,
Pesticide Application Data Table
Number of:
Size
Medium
Large
Color
Small
Black
Brown
Parental
Generation
10th Generation
2
22
1
22
3
5
20
0
24
1
20th Generation
10
15
0
25
0
30th Generation
23
2
0
25
0
Graph the data from the table above. YOU ONLY HAVE TO GRAPH THE SIZE DATA! Include a
key, and labels!
Number of Leafhoppers
Change in leafhopper body size with an increase in
temperature over 30 generations.
Generation
title,