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Oxford University Press - Online Resource Centres

Beeby & Beeby: Thrive in Ecology and Evolution

Excel models and calculations

Examples of the calculations described in the book are given here as Excel spreadsheets. Excel allows students to examine the detail of the calculation and manipulate the inputs (or the other elements of the calculation) to explore their effect on the outputs. In this way the workings of the calculations are transparent to the user and the method of manipulation is the same between different worksheets.

The equation or instruction applied to each cell can be viewed in the command line (the box adjacent to "fx" in the main window) at the top of each worksheet - clicking inside this formula highlights the calculation used to derive the contents of that cell. This will help you follow how the worksheet executes an equation.

A note on the models
We use finite difference equations to implement the population models discussed in the book, but offer a description of their derivation in an addendum below. This method becomes more problematical with multi-species models, especially the Lotka-Volterra model for predator-prey relations. If you are mathematically-minded, you will find the descriptions in the addendum helpful. Otherwise, simply use the implementation in the worksheets to explore some of the properties of the models.

A note on the presentation
We have used colour on our figures to ease navigation and identify data sets used to create the plot. This is not something we endorse for project or coursework: many of our past students would rightly complain that we never allowed them to submit multi-coloured figures in their work.
Guilty as charged. Our defence is that most peer-reviewed journals prefer authors submit black on white figures, so we believe students should develop their skills and ingenuity in presenting their data in monochrome. Other teachers may be more forgiving.

A note on Excel
None of the models or calculations use macro sub-routines, so no code is loaded onto your computer when you run these worksheets.

You will, of course, need MS Excel installed on your computer (these worksheets were written with MS Office Excel 2003 and should therefore be compatible with all later versions).

Click the links below to view each of the spreadsheets with a brief description and suggestions on how to use them. Also download and read the addendum to the Excel models.