Description

Activity descriptions

These activities are intended to accompany lessons on stage-structured populations. Activities are modular and editable; instructors can easily remove sections or questions that are not relevant to their course.

Version A

Part 1: This activity aims to show how life tables and stage-structured population models can be used to study local adaptation. In this activity, students are provided with data from a reciprocal transplant experiment on two subspecies of Gilia capitata (data from Nagy & Rice, 1997). These subspecies naturally occur in different habitats, and the experiment aims to determine whether they showed local adaptation. For each subspecies in each habitat, the researchers planted a predetermined number of seeds, and then noted the number of individuals surviving up to each subsequent life stage (emergence and flowering). Using this data, students are asked to create life tables and stage-structured populations models for each subspecies in each habitat. They then calculate the finite per-capita population growth rate and the net reproductive rate, thereby determining whether each subspecies show local adaptation.

Part 2: This activity aims to show how differential stage-specific vital rates affect a species persistence in different environments. Students work with the same two subspecies of Gilia capitata that were introduced in Part 1. They examine graphical climate predictions for each of the two sites where the subspecies are native to and then make predictions about how climate change could affect stage-specific survival and fecundity. Students then use a simulator (excel workbook or R Shiny app) to conduct a sensitivity analysis on survival rates or fecundity, to determine how much change would be required to cause the population decline.

Version B

Part 1: This activity aims to show how life tables can be used to study local adaptation. In this activity, students are provided with data from a reciprocal transplant experiment on two subspecies of Gilia capitata (data from Nagy & Rice, 1997). These subspecies naturally occur in different habitats, and the experiment aims to determine whether they showed local adaptation. For each subspecies in each habitat, the researchers planted a predetermined number of seeds, and then noted the number of individuals surviving up to each subsequent life stage (emergence and flowering). Using this data, students are asked to create life tables and calculate the net reproductive rate of each subspecies in each habitat, and thus determine whether the subspecies show local adaptation.

Part 2: This activity aims to show the importance of knowing a species’ life history and survivorship curve shape for conservation planning. It can also be used to teach sensitivity analysis. In this activity, students are presented with a conservation dilemma: “Suppose a population of an endangered species needs to be protected, but there are only enough resources to protect one life stage. Which life stage would you choose?”. They are then provided with life tables from three different populations: Gillia capitata (annual species; data from Nagy & Rice, 1997), bighorn sheep (long lived species with type I survivorship curve; data from Halley et al. 2018), monk seal (long lived species with type III survivorship curve; data from Halley et al. 2018). For each of these populations, students calculate the sensitivity of population growth rate to the survival rate or fecundity of each life stage. Based on the results of this sensitivity analysis, students are asked to answer the conservation dilemma presented at the beginning of the activity.

Files

Version A

• Student instructions and worksheet for part 1
• Student instructions and worksheet for part 2
• Instructor presentation
• Model simulator (excel spreadsheet)
• Life table answer key

Version B

• Student instructions and worksheet for part 1
• Student instructions and worksheet for part 2
• Instructor presentation
• Sensitivity analysis spreadsheet for students
• Answer key

Resources for both versions

• Model simulator R Shiny app and instructions for setting up this app

Prerequisite knowledge and skills

Before starting these activities students should be introduced to/be familiar with the following concepts:

• Age-structured and stage-structured population models

Additionally, for version A, students should have already been introduced to:

• How to construct a Leslie matrix from stage-specific survival rates and fecundity
• How to predict population growth from a given stage distribution using a Leslie matrix.
• How to calculate the per-capita pop. growth rate (????) from two sequential years of population sizes.

For version B, students should have been introduced to:

• Calculating survival rate and survivorship from a table of population size at (or number of individuals surviving up to) each life stage/age.
• Calculating net reproductive rate from survivorship and fecundity data.

Usage

The suggested timeline for using the complete set of activities follows:

Version A: Local adaptation and climate change impacts on Gilia capitata

Part 1: Evaluating Local Adaptation in Gilia capitata.

Use the version A instructor presentation to guide students through the worksheet. This will require at least 60 minutes:

• Calculate and discuss life table from experimental data (steps 1 - 2), 15 min
• Write stage-structured model from vital rates in life table (steps 3 - 4 ), 10 min
• Calculate annual population growth using model (steps 5 - 7), 20 min
  • Calculations of finite per-capita pop. growth rate (????) and net reproductive rate R₀ are both included, but the instructure may only want to include one of these. Note that Part 2 uses R₀.
• Compare and discuss population growth rates and local adaptation, 15 min

Part 2: Evaluating Climate Change Impacts on Gilia capitata

Assign this activity as homework or use it during a second class period. The activity will likely take a minimum of 65 minutes to complete. Prior to using this activity, the instructure will need to decide how students will simulate the population model. Two options are provided:

• An R Shiny application, which the instructor would need to host on their own shinyapps.io account. (Please see the README file in the R Shiny App Code zip file for more information).
• An Excel spreadsheet that students download (or access via Google Sheets) and interact with.

Once the simulation is set up, the instructor needs to edit the student instructions (see yellow highlight) to indicate which should be used.

Timeline:

• Learn how climate is changing in California and predict how this affects the biology of plant and its life cycle (Predictions section), 15 min
• Explore how changes in vital rates affect R₀ for one subspecies (Model Exploration section), 20 min
• Conduct a sensitivity analysis of one population vital rate for both subspecies living in the same location to determine which population is more resilient to climate change at that location (Model Sensitivity Analysis section), 20 min
• Discuss how this model is potentially unrealistic and what might be improved (Model Realism section), 10 min

Version B: Studying local adaptation and conservation planning with life tables

(This version is best suited for a lab course or a lab session where minimal lecture time is desirable.)

Part 1: Evaluating local adaptation in Gilia capitata. ~50-65 mins

Timeline:

• Use version B instructor presentation (slides 1-21) to guide students through the activity. 20 mins
• Ask students to fill out the version B part I worksheet. This will involve calculating survival rates and survivorship for each life stage of each Gilia population, and then calculating net reproductive rate. 30 mins
• Compare and discuss population growth rates and local adaptation. 15 mins or homework

Part 2: Conservation planning using life tables ~40-60 mins

Timeline:

• Use version B instructor presentation (slides 22-28) to guide students through the activity. 10 mins
• Ask students to fill out the version B part II worksheet. For scenario 1, students can either use the R Shiny app, or carry out calculations by hand. (Please see the README file in the R Shiny App Code zip file for instructions of using the R Shiny app). For scenarios 2 and 3, the Version B Part II Excel worksheet would need to be used (calculating by hand would be too tedious). 30 mins
• Compare and discuss the results of the sensitivity analysis and the importance of life tables for conservation planning. 15 mins

Data References

Nagy E. S. and K. J. Rice. 1997. Local adaptation in two subspecies of an annual plant: implications for migration and gene flow. Evolution 51: 1079-1089. Doi: 10.1111/j.1558-5646.1997.tb03955.x.

Halley, John M., Kyle S. Van Houtan, and Nate Mantua. 2018. "How survival curves affect populations’ vulnerability to climate change." PLoS One 13.9: e0203124.

Notes

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