bellwork (on back of last week’s )

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Bellwork (on back of last week’s) 1. Which level(s) have the most organisms? Think back to trophic levels… 2. So how do you estimate HUGE population sizes???

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Bellwork (on back of last week’s ). Think back to trophic levels…. 1. Which level(s) have the most organisms?. 2. So how do you estimate HUGE population sizes??? . Human populations are estimated using census & hospital records…what about other organisms?. Mark & Recapture. - PowerPoint PPT Presentation

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Page 1: Bellwork (on back  of last  week’s )

Bellwork (on back of last week’s)

1. Which level(s) have the most organisms?

Think back to trophic levels…

2. So how do you estimate HUGE

population sizes???

Page 2: Bellwork (on back  of last  week’s )

Human populations are estimated using census & hospital records…what about other organisms?

Page 3: Bellwork (on back  of last  week’s )

Mark & RecaptureQuestion: What is the size of the cricket population

in the aquarium?

Page 4: Bellwork (on back  of last  week’s )
Page 5: Bellwork (on back  of last  week’s )

Female vs Male

Ovipositor

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Procedures1. Take a “trap” out of aquarium, & shake ALL crickets

into container (beaker)2. Take crickets to lab table & mark w/ a dot of nail

polish (see board for marking instructions)

Page 7: Bellwork (on back  of last  week’s )

p.1- Thorax (rectangular tank)p.2- Thorax (hexagon tank)p.3- right or left hind leg (rectangular tank)p.4- underneath abdomen (rectangular tank)p.6- underneath abdomen (hexagon tank)

Page 8: Bellwork (on back  of last  week’s )

Procedures1. Take a “trap” out of aquarium, & shake ALL crickets

into container (beaker)2. Take crickets to lab table & mark w/ a dot of nail

polish (see board for marking instructions)3. Record data about crickets’ sex (1st capture)

4. Put crickets back into aquarium & add group info to board

Get started!

Page 9: Bellwork (on back  of last  week’s )

Mark & RecaptureQuestion: What is the size of the cricket population

in the aquarium?

Mark & Recapture: a method of estimating animal population size by:

1. Capturing, marking & releasing 1st group2. Later capture another group, & analyze

how many were “recaptured” (have marks)

Page 10: Bellwork (on back  of last  week’s )

Why estimate population sizes?• Give as many reasons as you can think ofHunting Permits

Endangered Species

Assess impact of Disasters, Disease,

Climate Change

Assess health of environment

To learn!

Page 11: Bellwork (on back  of last  week’s )

Background InformationAssumptions:1. Population is closed (no immigration/emigration)2. Marks are not lost or overlooked3. All animals equally likely to be captured both times

Page 12: Bellwork (on back  of last  week’s )

Background Information:Variables:n1= # animals marked & released 1st timen2= # animals captured 2nd timem2= # animals w/ original mark 2nd time (# recaptured)

N= estimate of population size

N = n1 x n2

m2Equation:

Page 13: Bellwork (on back  of last  week’s )

Example• A biologist wants to estimate the size of a population of turtles in a lake.

She captures 10 turtles on her first visit to the lake, and marks their backs with paint. A week later she returns to the lake and captures 15 turtles. Five of these 15 turtles have paint on their backs, indicating that they are recaptured animals.

• Turtle Population Estimate: N=30

N = n1 x n2

m2 N = 10 x 15

5

Page 14: Bellwork (on back  of last  week’s )

What can go wrong?Think about the assumptions…tell your neighbor a

real life example of something that could throw off a population estimate?

How would “trap-happy” individuals change the population estimate?

I really like that trap! It’s so warm &

cozy…

N = n1 x n2

m2

Page 15: Bellwork (on back  of last  week’s )

Procedures5. Wait 15-20 minutes, then take out a trap & put ALL

crickets from trap into container6. Record how many crickets are marked with your

class period’s marking.7. Put away crickets & come back to desk to work on

conclusion. Add group info to board

Get started!

Page 16: Bellwork (on back  of last  week’s )

Let’s calculate!• n1 = class total from 1st capture• n2 = Class total from 2nd capture• m2= Class total from 2nd capture that were marked

• Calculate under Q #1 on back- show equation & work!

Finish conclusion questions in

complete sentences

Page 17: Bellwork (on back  of last  week’s )

Closure

Pretend you are the teacher…

Write a challenging test question that assesses a student’s understanding of the mark & recapture method, & ability to calculate a population size. Include an answer key.