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Pages 398-400 How study ecology?

Pages 398-400 How study ecology?. Ecological research methods include: *a. observation *b. experimentation *c. modeling. Observation. Visual surveys * direct surveys – used for species that are easy to see/follow * indirect surveys – used for species that are difficult to track

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Pages 398-400 How study ecology?

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  1. Pages 398-400How study ecology? Ecological research methods include: *a. observation *b. experimentation *c. modeling

  2. Observation • Visual surveys *direct surveys – used for species that are easy to see/follow *indirect surveys – used for species that are difficult to track ex. radio telemetry • Scientists use sampling to represent larger populations *mark and recapture *quadrat use – see page 401, work problems…

  3. Answers to page 401, #1 and #2 at bottom: 1442 individuals 11.53 x 125 = 1441.67 173/15=11.53=N 250/2 = 125= A ------------------------------------------------------ 12,600 individuals 6.3 x 2000 = 12,600 63/10 = 6.3 = N 500/0.25 =2000=A

  4. Population Sampling • Usually, the population is too large for the researcher to attempt to survey all of its members. • A small, but carefully chosen sample can be used to represent the population. • The sample reflects the characteristics of the population from which it is drawn

  5. Population Sampling • Sometimes, the entire population to be studied is small enough for the researcher to include the entire population in the study. • This type of research is called a census study because data is gathered on every member of the population.

  6. The most common sampling method is: Random Sampling • It gives you a “best estimate” of the population size

  7. Bias in Sampling What does “bias” mean?Which of these populations was bias sampled? Bias occurs when samples that are collected to determine distribution are selected incorrectly and do not represent an actual group – the sample must be RANDOMLY selected and represent an entire group!

  8. b. Experimentation • Experiments are performed in the lab or in the field Lab experiments are conducted in a controlled, indoor environment Field experiments are performed where the organisms live – MUCH more difficult to control this type…

  9. c. Modeling • If answers cannot be easily obtained with observation or experiments, scientists will use models to learn about organisms or whole ecosystems *models rely on computers and mathematical formulas

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