bellwork (on back of last week’s )
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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 PresentationTRANSCRIPT
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???
Human populations are estimated using census & hospital records…what about other organisms?
Mark & RecaptureQuestion: What is the size of the cricket population
in the aquarium?
Female vs Male
Ovipositor
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)
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)
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!
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)
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!
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
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:
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
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
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!
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
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.