Practice System Interactions: Population Dynamics Lab Instructions

Lab)Lab Objectives

Before doing this lab you should understand:

- Type I, Type II, and Type III survivorship curves
- semi-log graph

Lab Objectives

After doing this lab you should be able to:

- analyze mortality data and extract information to create survivorship curves
- compare and contrast male and female survivorship
- evaluate data for validity and suggest improvements to data-collection method

Materials

This is a hands-on lab experience in which you will be analyzing survivorship based on data provided by a cemetery.

You will need:

- a cemetery (or access to cemetery records)
- a calculator
- a pencil or pen
- paper

Background Information

Age-structure information about a population can be very helpful in analyzing its potential to persist and grow. By recording data on mortality rates for different age groups, it is possible to construct a survivorship curve for a population.

Procedure

**Note:** For the calculations in your lab, remember to set up the problem correctly, using units of measurement and showing all steps of the work. **Showing steps for solving the problem is a requirement **

- Visit a nearby cemetery (be sure to call ahead to ask permission first) and collect data from at least 100 different gravestones (find 50 males and 50 females). You should note the gender and the age at death. Organize your data into a table like this (it is easiest to use tally marks):

**AgeNumber of males who died at this ageNumber of females who died at this age**0 to 5 years old 5 to 10 years old 10 to 15 years old, etc., by five-year intervals up to your oldest data point

- If a cemetery is not near your home or you prefer not to visit a cemetery, use the data from the Cazenovia cemetery and randomly choose 100 different individuals (50 males and 50 females) to complete the data table.
- Analyze your data in terms of survivorship, like this:

AgeNumber of males who died at this ageNumber of males surviving at this age = 50 - number of males who died up to this agePercent surviving at this age = number of males surviving divided by 50, times 100

**There needs to be a table like this for the females also.**

- Create survivorship curves by plotting percent surviving (on the
*y*-axis) versus age (*x*-axis). There needs to be graph for males and a graph for females, or, if possible, you can graph the male and female curves on the same graph (be sure to include a legend or key).

Reflection Questions:

- Compare the male and female survivorship curves. Discuss any differences or similarities.
- How valid are these survivorship curves? What factors might affect their accuracy?
- What type of survivorship does your curve show? Is this what you expected?
- Discuss ways to explore the information obtained in more depth.
- How do you think the data would change if we focused on individuals born now and followed their survivorship patterns into the future?

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