Population Growth
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Level 4 Guiding Question: How can scientists keep track of so many different populations?
Click on the button below to read the online chapter that will help you answer the questions in google form.
Population Growth Introduction
Read the above article about Population Growth and answer the questions below:
Level 4 Investigation: Introduction to Estimating Animal Populations Ecologist often spend time out in the field studying the various biotic and abiotic components that make up the ecosystems that they are interested in researching. Such factors may include things like water quality, soil type, and various species of plants and animals. One important element of an ecosystem that scientists may be interested in is animal populations. They may want to know how many individuals of a particular species reside in a specific habitat.
Researchers may find such information important to understanding an ecosystem’s food web, or the scientists may want to use population data to determine whether or not a threatened species is declining. Observed population fluctuations may be normal or they may indicate that the ecosystem is out of balance. Unfortunately there is no easy way to count all the members of an animal population in an ecosystem. Animals move from place to place; they hide, they hibernate, and they camouflage themselves. Surveying a large tract of land trying to count all the members of a species would be extremely time consuming and expensive. In other words, conducting a census, which is the counting of every single individual in a population, is simply impractical if not impossible. So researches have developed a more efficient method. This method is called the capture-mark-recapture technique and is used to make a meaningful estimate of an area’s animal population. With the capture-mark-recapture method, instead of trying to count every animal in an ecosystem, you randomly capture a sample group of the population, mark it, release it, and then do a series of recaptures that will allow you to estimate the entire population under study. Scientists must capture animals carefully in an effort to avoid injury and trauma. A wide variety of techniques are used to mark animals that have been captured. Birds will have small bands put around their legs, fish will have one of their small fins clipped, mice and rats will have their tails painted, tortoises will have their shells tagged, and larger mammals may have collars attached. Once a sample group has been tagged, they are then released back into the ecosystem from where they were captured. Scientists then wait for a period of time which could range from a few days to several weeks at the end of which they capture a second group of the same species. (Note: This second capture does not have to be the exact same number captured the first time. For example, a researcher might capture 72 mice the first time and 60 mice the second time.) The second group, the recapture, will contain some animals that were captured the first time and some that were not. This will be obvious because the ones captured the first time will be marked. The ratio between the marked and unmarked animals is the key to estimating the species population for the entire ecosystem. For example, as mentioned above, let’s say on your second capture you get a total of 60 animals. After checking carefully, you discover that a quarter or 15 of the 60 are marked and had therefore been captured the first time. This recapture should be a random representation of the entire population with the marked individuals in the recapture representing the first capture’s proportion of the population. Going back to our example, this would mean that the 15 marked individuals in the recapture indicate to us that the first group captured represents 25% of the total population. To estimate the population for the entire ecosystem, divide the number in your first capture, let’s say 72, by 0.25 (25%). If you do this, you get an estimated population for the entire ecosystem of 288 individuals of the species you are counting. To get greater accuracy you would want to do several recaptures and get an average ratio between the marked and unmarked animals. |
How snails are marked for study
How to calculate Population Growth
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Level 4 Investigations: Estimating Animal Populations Lab
Please carefully read the lab activity below you will be working at your table groups. Print out the lab one for each table group and record your results on the data sheet provided on the back two pages of the lab. Please keep these because you will need to upload your data at a later date. Watch the video below to help you with the setup and data analysis.
Level 4 Investigations: Estimating Animal Populations Data Sheet
Read the above lab and use the paper data sheet to collect your results and math then upload to the data sheet below.
Level 4 Videos: Sampling a Population
Sampling a deer population
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Capture and Recapture Technique
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View this video to help you perform the lab ("Estimating Animal Population") and its analysis please press play.
Level 4 Elaborate: Make a tutorial video
You are to make a tutorial video (using your phone or iPad) on Estimating Animal population using the capture/recapture method. If you were in charge of a team given the responsibility to determine the number of Red Drum (redfish) in the Gulf of Mexico, discuss with your audience how would you accomplish this task and describe in detail. In addition, you will show how to do the mathematics (scientific estimate and % Error).
Level 4 Review
Click on the button below Practice Quizzes
Level 4 Summary
Unit Test
Assignments for this Unit: Due by Friday 11-7
-Did you know? Blog Alert: Click on the blog button and post on answer to the following question: "Why is it important to know current world population trends?"
-Level 4 Guiding Question: How can scientists keep track of so many different populations? Read the text in chapter entitled, "Population Growth" and complete the form underneath it.
-Level 4 Investigations: Do the lab entitled, "Estimating Animal Populations Lab" and entered the results and analysis in the form called, "Estimating Animal Populations Data Sheet".
-Level 4 Elaborate: Make a tutorial video
-Level 4 Summary: Unit quiz
-Level 4 Guiding Question: How can scientists keep track of so many different populations? Read the text in chapter entitled, "Population Growth" and complete the form underneath it.
-Level 4 Investigations: Do the lab entitled, "Estimating Animal Populations Lab" and entered the results and analysis in the form called, "Estimating Animal Populations Data Sheet".
-Level 4 Elaborate: Make a tutorial video
-Level 4 Summary: Unit quiz