POPULATIONS LESSON 2 - SAMPLING A critical appreciation of some of the ways in which the numbers and distribution of organisms may be investigated. Random sampling with quadrats and counting along transects to obtain quantitative data. The use of percentage cover and frequency as measures of abundance. The use of mark–release–recapture for more mobile species. In the context of investigating populations, candidates should carry out experimental and investigative activities, including appropriate risk management consider ethical issues arising when carrying out fieldwork, particularly those relating to the organisms involved and their environment analyse and interpret data relating to the distribution of organisms, recognising correlations and causal relationships appreciate the tentative nature of conclusions that may be drawn from such data.

Lets get started: Measuring Populations  I have given you a garden in which I would like you to measure the population of  Dandelions  Grass  Beetles Write a brief thought on how you would estimate the population numbers for each of these organisms. Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

Quadrats and Transects  Considerations of using Quadrats  How do we get a random sample?  Systematic sampling along transects. Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

Measuring Abundance  Counting individual plants is one way of measuring the abundance.  There are simpler ways:  Frequency: the likelihood of species occurring in the quadrat (if the species is in 15 out of 30 quadrats sampled, Frequency is 50%)  Percentage cover: an estimate of an area in one quadrat that the species covers. (e.g. the species covers 10 of 25 squares, Percentage cover is 40%) Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

Plenary – Write a method for using quadrats and transects Exam question: Explain a method you could use to measure the population of dandelions in an ecosystem.  Write a method for random sampling using frame quadrats and systematic sampling using transects. (quadrat, transect, random, abundance, percentage cover, frequency, large sample size/multiple quadrats) Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

QUADRATS AND TRANSECTS 1.Use the point quadrat to count the number of dandelion species 2.Use your frame quadrats randomly sampled to count the number of dandelions in this environment. Do this 3 times. 3.Now use the transect to measure the number of dandelions across different zones

Lets get started: Sampling animals. Q: Can you use quadrats for animals? What problems would this pose? Mind map your ideas here. Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling 2A4

Mark-release- recapture method  Animals are hard to count by quadrats, so you can use the Mark-release- recapture method. 1. Collect a sample of ‘animals’. 2. Count/note how many you collect and mark each one in some way (n1) 3. Release the ‘animals’ back into the area. 4. Collect a second sample later, count/note how many of these there are (n2) 5. Also count/note how many of these were marked in the first sample (n3). 6. Use this equation to estimate the overall population size. Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

Assumptions that have to be made  Q: In order for your estimate to be accurate, what things would you have to assume are true:  Proportion of marked-unmarked in second sample is the same in the whole population  The marked individuals are fully re- distributed into the ecosystem before second sampling.  No individuals can immigrate or emigrate out or into the ecosystem  There are no deaths and births  Marking does not harm the animal or make it more vulnerable to predation  The marking does not rub off. Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

Ethics of sampling Q: what are the ethical implications in doing field work?  Ways to minimise the impact of fieldwork on the ecosystem:  Organisms studied in situ. Try not to remove any organisms if possible.  Any organisms that are removed, should be returned as soon as possible, even if dead.  A sufficient amount of time before a secondary study is undertaken as to minimise any disturbances.  Avoid damaging and disturbing habitats, e.g. overturning stones, trampling, litter etc. Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling

Plenary – Exam question  Page 24 Question 2  DO NOW!! Outcomes: -Outline the method for investigating populations using quadrats and transect sampling. Noting the importance of having a large sample size and risk management -Compare the different methods of measuring abundance in quadrat sampling, noting advantages and disadvantages of each. -Explain the mark-release- recapture method for sampling animals -Consider and discuss the ethics surrounding sampling