A bumblebee feeding on the orange centre of a purple coneflower

ENVIRONMENTAL SCIENCE · CHAPTER 5

Species Interactions Lab

Follow along with your worksheet, one question at a time.

mrsajdak.com/interactions

Photo: Jim Hudgins, U.S. Fish and Wildlife Service

BEFORE YOU START

No species lives alone

A red lady beetle with black spots walking across a green leaf covered in small green aphids

Lady beetle, aphids

A lady beetle walks through a crowd of aphids.

Hands holding a lake trout with two long dark sea lampreys hanging from its side

Lampreys, lake trout

Two sea lampreys hang on to one living trout.

A robin sitting on a nest built in the fork of a tree

Robin, tree

A robin sits on its nest in a tree.

The sign code

+  does better with the other one

−  does worse with the other one

0  no change

Each species in a pair gets its own sign.

Who is helped? Who is hurt? How could you find out?

Photos: Whitney Cranshaw, Colorado State University, CC BY 3.0 US · Great Lakes Fishery Commission · Shenandoah National Park

BEFORE YOU START

Get set up

1

Open mrsajdak.com/interactions on your device.

2

Write your name, the date and your period on the worksheet.

3

Find the tabs at the top of the lab. The table shows which tab goes with each part.

4

Start on Tab 1. Do not skip ahead.

The top of the lab page, showing the title and three tabs: Take one away, Mystery pairs, Sharing a tree
Tab in the labWorksheetQuestions
1. Take one awayParts 1 and 21 to 8
2. Mystery pairsPart 39 to 11
3. Sharing a treePart 412 to 14
1. Take one awayWrap it up15 and 16

Screenshot: mrsajdak.com/interactions

Tall spikes of purple loosestrife flowers growing at the edge of a marsh

TAB 1 · QUESTIONS 1 TO 4

Part 1. Take one away

Scientists compare two places. One has both species. One is missing a species.

You will do the same thing in a model, with five pairs.

Photo: Todd Harless, U.S. Fish and Wildlife Service

PART 1 · TAB 1

Three runs for every pair

1

In Pick a pair, pick Lady beetles + aphids.

2

Both species are checked. Press Skip to the end.

3

Uncheck one species. That takes it away. Press Skip to the end again.

4

Check it again. Uncheck the other one. Press Skip to the end.

5

Do the same three runs for all five pairs.

The Pick a pair box in the lab, with five buttons: Lady beetles + aphids, Bumblebees + coneflowers, Sea lampreys + lake trout, Robins + street maples, Purple loosestrife + cattails The In the habitat box in the lab, with Lady beetles unchecked and Aphids checked, a run button, a Skip to the end button and a speed choice
Milkweed plants in the lab on day 5 with aphids on the stems. The box in the corner says lady beetles are taken away

Run plays it slowly so you can watch. Skip to the end jumps to the last day or year.

The box in the corner of the picture shows the counts. A species you unchecked says taken away.

Screenshots: mrsajdak.com/interactions, Tab 1

PART 1 · QUESTION 1

Fill in the table

1

Find the Your runs box. It gets one row for each run.

2

Alone is the number in the row that ends in only.

3

With the other is the number in the row Both together.

4

Compare the two numbers. More with the other is +. Fewer is −. The same is 0.

The Your runs box in the lab before any runs, with a column for who was in the habitat and a column for each species

The numbers stay when you switch pairs. They are gone if you reload the page.

Example

A species ends at 12 when it is alone.

It ends at 30 with the other one.

12 alone, 30 together

It does better with the other. Its sign is +.

These are not your numbers. Use your own.

Screenshot: mrsajdak.com/interactions, Tab 1

PART 1 · QUESTION 1

Name the interaction

1

Find the Your call box.

2

Press +, − or 0 for each species.

3

Pick a name from the list.

4

Press Check. Fix it if the lab says to look again.

5

Write the name in the last column of your table.

The Your call box in the lab: plus, minus and zero buttons for each species, a list that says Name it, and a Check button

Check works only after all three runs for that pair.

NameSigns
Mutualism+  +
Commensalism+  0
Predation+  −
Parasitism+  −
Competition−  −

These names are on your worksheet too.

Screenshot: mrsajdak.com/interactions, Tab 1

PART 1 · QUESTIONS 2 TO 4

Explain what you saw

QUESTION 2

0

No change

Find the street maples in your table. Compare alone and with robins.

What does a 0 tell you about what robins do to the maples?

QUESTION 3

+ −

Same signs, two names

Use Run, not Skip. Watch the habitat. Read the words under the picture.

What does a lady beetle do to an aphid? What does a lamprey do to a trout?

QUESTION 4

− −

Who was hurt more?

Loosestrife and cattails both did worse together.

For each plant, subtract: alone minus with the other. Use the numbers.

A thin plant stem covered from end to end with hundreds of small yellow aphids

TAB 1 · QUESTIONS 5 TO 8

Part 2. Boom and crash

Stay on Tab 1. Pick Lady beetles + aphids. Check both species.

This time, do not skip. Watch the numbers climb and fall.

Photo: Malcolm Manners, CC BY 2.0

PART 2 · QUESTION 5

Find the highest counts

1

Press Run. Watch the graph called Population over time.

2

The box in the corner of the picture shows the day and both counts.

3

Press Pause when a line is near its top. Write the count and the day.

4

Press Keep going. Do the same for the other species.

5

Missed it? Press Run again.

The Population over time graph in the lab, stopped early in a run. A yellow line for aphids is climbing and a red line for lady beetles is still low

Example

90 on day 12

A line tops out at 90 when the box says Day 12. Not your numbers.

The yellow line is aphids. The red line is lady beetles. Solid lines are both together.

Screenshot: mrsajdak.com/interactions, Tab 1

PART 2 · QUESTIONS 6 AND 7

Why the lines do that

QUESTION 6

Which peaked first?

Look at your two days from Question 5.

Lady beetles eat aphids. What has to happen before there can be more lady beetles?

QUESTION 7

Carrying capacity

In Your runs, find the row Aphids only. Write that number. It is the carrying capacity.

On the graph, the dashed yellow line is the aphids alone. The solid yellow line is the aphids with lady beetles. Which one stays lower?

Milkweed plants in the lab on day 9, with many yellow aphids on the stems and three red lady beetles

Each dot on a stem is an aphid. A red ring shows a lady beetle eating one.

Dashed lines on the graph are your runs with one species taken away.

Screenshot: mrsajdak.com/interactions, Tab 1

PART 2 · QUESTION 8

What did the lampreys cost?

1

Pick Sea lampreys + lake trout. Your three runs are still in Your runs.

2

Write the trout number from Lake trout only. Write the trout number from Both together.

3

Subtract. That is how many trout were lost.

4

Divide by the alone number. Multiply by 100. Show your work.

A lake in the lab in year 4, full of swimming lake trout with a few dark sea lampreys among them

A lamprey rides on a trout. A trout that dies turns pale and floats up.

Example

Alone, a species ends at 200.

With the other one, it ends at 150.

200 − 150 = 50
50 ÷ 200 = 0.25

The other species cost it 25%.

These are not your numbers. Use your own.

Screenshot: mrsajdak.com/interactions, Tab 1

A wildlife biologist in uniform writing counts on a clipboard outdoors

TAB 2 · QUESTIONS 9 TO 11

Part 3. Mystery pairs

Scientists count first. Then they decide.

You get two real species with their names hidden. The numbers are your only evidence.

Photo: Ashley Spratt, U.S. Fish and Wildlife Service

PART 3 · QUESTION 9

Solve a mystery pair

1

Open Tab 2. Species X is the teal diamond. Species Y is the orange circle.

2

Do three runs: both together, X alone, Y alone.

3

Copy the four numbers from Your runs. Write the signs.

4

Make your call in Your call. Press Check.

5

Then press Reveal. Write the real names.

6

Press New mystery pair. Do it again for trial 2.

The Mystery pair box in the lab, with a New mystery pair button The Your call box on the mystery tab: plus, minus and zero buttons for species X and species Y, a list of names, a Check button and a Reveal button
The mystery habitat in the lab in year 3: teal diamonds and orange circles on a plain grid, with the words Names hidden

X alone means Y is unchecked.

The lab picks your pair at random. Your neighbor may get a different one.

Screenshots: mrsajdak.com/interactions, Tab 2

PART 3 · QUESTION 10

Claim, evidence, reasoning

Claim

Pick one trial. Name the interaction. Use one of the five names.

Evidence

Give four numbers from your table: X alone, X with Y, Y alone, Y with X.

Reasoning

Tie each change to a sign. More with the other is +. Fewer is −. The same is 0. Then say which name has those signs.

Example

X ends at 10 alone and 50 with Y. That is a +.

Y ends at 80 alone and 80 with X. That is a 0.

+ and 0

Those are the signs for commensalism.

These are not your numbers. Use your own.

PART 3 · QUESTION 11

Same signs, different story

A lake trout lying on a net with a dark sea lamprey attached to its side

QUESTION 11

Can the numbers tell them apart?

Predation has the signs + and −. So does parasitism.

Think back to Question 3. How did you tell the lady beetle from the lamprey?

What else would a scientist need to see?

After you press Reveal, read the story about your pair. It tells what the two species really do.

Photo: U.S. Fish and Wildlife Service

A small brown and yellow warbler perched on a bare pine branch

TAB 3 · QUESTIONS 12 TO 14

Part 4. Sharing a tree

Three kinds of warbler eat insects in the same spruce trees.

Can all three live there? It depends on how they feed.

Photo: Courtney Celley, U.S. Fish and Wildlife Service

PART 4 · QUESTION 12

Two ways to feed

1

Open Tab 3. Keep all three warblers checked.

2

In How do they feed?, pick Anywhere in the tree.

3

Press Skip to the end. The run ends at year 50.

4

Pick Each in its own part. Press Skip to the end again.

5

Copy both rows from Your runs.

The How do they feed box in the lab, with two choices: Anywhere in the tree, and Each in its own part

Your runs lists both ways. Look for Anywhere and Own part.

A spruce tree in the lab in year 3, split by dashed lines into treetop, middle and lower branches, with a different kind of warbler in each part

The dashed lines mark the three parts: treetop, middle and lower branches.

Screenshots: mrsajdak.com/interactions, Tab 3

PART 4 · QUESTIONS 13 AND 14

Why sharing works

QUESTION 13

Same food

Feeding anywhere

Look at your first row. What happened to two of the warblers?

Why? Use the word competition.

QUESTION 14

Own part

Resource partitioning

Resource partitioning means splitting up food or space.

Look at your second row. How does it let all three live in one tree?

A spruce tree in the lab in year 2, with three kinds of warbler mixed together all over the tree

Year 2 with Anywhere in the tree. All three kinds hunt in the same places.

Screenshot: mrsajdak.com/interactions, Tab 3

WRAP IT UP · QUESTIONS 15 AND 16

Predict, test and argue

Predict

Since 1958, crews have treated streams to kill young sea lampreys. What happens to the lake trout if all the lampreys are gone? Write it first.

Test

Go to Tab 1. Pick Sea lampreys + lake trout. Uncheck Sea lampreys and run it. Were you right?

The claim

“In every interaction, one species wins and one species loses.”

Argue

Use two pairs from your Question 1 table. Find pairs where the signs are not one + and one −.

Two workers in life jackets and masks on a small boat treating the water near a forested shore

A crew treats the water to kill young sea lampreys.

Photo: U.S. Fish and Wildlife Service

Bumblebees feeding on a patch of purple coneflowers in a sunny meadow

LAST CHECK

Before you hand it in

Name, date and period are on top.

All three tables are full.

Question 8 shows your work.

Every claim uses numbers or signs from your own tables.

Photo: Debbie Koenigs, U.S. Fish and Wildlife Service