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

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Mark & Recapture Question: What is the size of the cricket population in the aquarium?

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Female vs Male Ovipositor

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Procedures 1.Take a “trap” out of aquarium, & shake ALL crickets into container (Ms. D’s job) 2.Take crickets to lab table & mark w/ a dot of nail polish: ________________________

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p.1- left hind leg (rectangular tank) p.2- left hind leg (hexagon tank) p.3- thorax (rectangular tank) p.4- right hind leg (rectangular tank) p.6- thorax (hexagon tank)

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Procedures 1.Take a “trap” out of aquarium, & shake ALL crickets into container (Ms. D’s job) 2.Take crickets to lab table & mark w/ a dot of nail polish 3.Record data about crickets’ sex (1 st capture) 4.Put crickets back into aquarium & add group info to board Get started!

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Mark & Recapture Question: 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 group 2. Later capture another group, & analyze how many were “recaptured” (have marks)

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Why estimate population sizes? Give as many reasons as you can think of Hunting Permits Endangered Species Assess impact of Disasters, Disease, Climate Change Assess health of environment To learn!

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Background Information Assumptions: 1.Population is closed (no immigration/emigration) 2.Marks are not lost or overlooked 3.All animals equally likely to be captured both times

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Background Information: Variables: n1= # animals marked & released 1 st time n2= # animals captured 2 nd time m2= # animals w/ original mark 2 nd time (# recaptured) N= estimate of population size N = n1 x n2 m2 Equation:

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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

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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

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Procedures 5. Wait 15-20 minutes, then take out a trap & put ALL crickets from trap into container 6. 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!

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Let’s calculate! n1 = class total from 1 st capture n2 = Class total from 2 nd capture m2= Class total from 2 nd capture that were marked Calculate under Q #1 on back- show equation & work! Finish conclusion questions in complete sentences

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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. Closure

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STUDYING POPULATIONS. DETERMINING POPULATION SIZE Some methods of determining the size of a population are direct and indirect observations, sampling.

STUDYING POPULATIONS. DETERMINING POPULATION SIZE Some methods of determining the size of a population are direct and indirect observations, sampling.

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