Topic 4 Measuring Populations Sampling populations of different
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Topic 4 Measuring Populations Sampling populations of different species using different methods.
Topic 4 b Measuring Populations: MARK AND CAPTURE METHOD Key Concepts Vocab • Why do we sample populations? • What are the ways in which we measure a non-mobile population? • What are the ways in which we measure a mobile population? • What are benefits & drawbacks to these methods? • • Sampling Quadrat Mark & capture Mobile/Nonmobile
Capture-Mark-Release-Recapture • Scientists capture, mark, and release individuals in a population • Individuals are then recaptured and marked members are used to estimate population size. • Equation: n 1 x n 2 Population size = ----n 3 n 1= # caught and marked 1 st time (capture and mark) N 2 = Tot # caught 2 nd Time (recapture) N 3 = # of marked organisms from the recapture
EXAMPLE: Capture-Mark-Release-Recapture 3. RELEASE 1. CAPTURE 2. MARK (NOT VISIBLE TO PREDATORS) 4. RE-CAPTURE 5. CALCULATE
Mark – Capture - Recapture PRACTICE PROMBLEMS
Mark/Capture/Recapture Example Problems DAY 1 DAY 2
Mark/Capture/Release/Recapture Evaluation: Strengths: q. Estimates the population. q. Efficiency (saves time) q Saves money Limitations: q. Marks can be lost by molting, rain, skewed results q. Marked can be more noticeable to predators q. Only works with a static (unchanging) population
Evaluation: Quadrats Strengths: q Estimates the population q Efficiency (saves time) q Saves money Limitations: q Less money = Less Accuracy q Skewed results can happen if: a. smaller sample size b. no random sampling, c. Population is clumped.