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Bellwork (on back of last weeks ). 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 recordswhat about other organisms?. Mark & Recapture. - PowerPoint PPT Presentation

Transcript of Bellwork (on back of last week’s )

Diapositiva 1

Bellwork (on back of last weeks)

1. Which level(s) have the most organisms?Think back to trophic levels2. So how do you estimate HUGE population sizes??? Human populations are estimated using census & hospital recordswhat about other organisms?

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

Teacher Notes:Materials = 1 large aquarium, 50 crickets, 8 traps (like egg carton pieces/cardboard w/ crevices), & a way to mark the crickets (nail polish, paint pen, etc.)3

Female vs Male

OvipositorProceduresTake a trap out of aquarium, & shake ALL crickets into container (beaker)Take crickets to lab table & mark w/ a dot of nail polish (see board for marking instructions)

-Suggestion: Mark crickets in different location each class period (thorax in one class, left jumping leg in another, etc.)-Give rest of info (on following slides) after students do 1st capture & mark, so the crickets can settle back in for 15-20 minutes before recapture6

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)ProceduresTake a trap out of aquarium, & shake ALL crickets into container (beaker)Take crickets to lab table & mark w/ a dot of nail polish (see board for marking instructions)Record data about crickets sex (1st capture)Put crickets back into aquarium & add group info to board

Get started!-Suggestion: Mark crickets in different location each class period (thorax in one class, left jumping leg in another, etc.)-Give rest of info (on following slides) after students do 1st capture & mark, so the crickets can settle back in for 15-20 minutes before recapture8Mark & 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)

Teacher Notes:Materials = 1 large aquarium, 50 crickets, 8 traps (like egg carton pieces/cardboard w/ crevices), & a way to mark the crickets (nail polish, paint pen, etc.)9Why estimate population sizes?Give as many reasons as you can think of

Hunting PermitsEndangered SpeciesAssess impact of Disasters, Disease, Climate ChangeAssess health of environmentTo learn!10Background InformationAssumptions:Population is closed (no immigration/emigration)Marks are not lost or overlookedAll 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 n2m2Equation: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 n2m2N = 10 x 155

What can go wrong?Think about the assumptionstell 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! Its so warm & cozyN = n1 x n2m2Examples of things that can go wrong: immigration/emigration occurs between capturing periods, marks get rubbed off or overlooked, certain individuals may be trap-happy (more likely to get caught)14Procedures5. 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 periods marking.7. Put away crickets & come back to desk to work on conclusion. Add group info to board

Get started!-Suggestion: Mark crickets in different location each class period (thorax in one class, left jumping leg in another, etc.)-Give rest of info (on following slides) after students do 1st capture & mark, so the crickets can settle back in for 15-20 minutes before recapture15Lets calculate!n1 = class total from 1st capturen2 = Class total from 2nd capturem2= Class total from 2nd capture that were marked

Calculate under Q #1 on back- show equation & work!Finish conclusion questions in complete sentencesClosurePretend you are the teacher

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