Presentation on theme: "Biodiversity Part II The National Institute for Mathematical and Biological Synthesis."— Presentation transcript:
Biodiversity Part II The National Institute for Mathematical and Biological Synthesis
Dealing with Large Data Sets Oftentimes you are working with large data sets that require analyses using special tools. We are going to work with a data set that spans several years to see if we can say something about the biodiversity of salamanders in the Great Smoky Mountains National Park. We are going to use Microsoft Excel to make calculations using more data than we used in part I.
First lets take a look at the data:
Data explanation: The data is arranged in an excel spreadsheet for two sites in the GSMNP. The first column, A, is from the Pig Pen site and the E column is from the second site, the Lower Dorsey. The names are salamander species in the columns. Column B and column F give the number of individuals of each species counted for the year 2000, with the column name denoted n.
We have this data over several years. We can ask many questions about how the biodiversity of salamander populations have changed over the years in the GSMNP. We can look at Simpsons Index and compare the two sites for each year and we can also see if the biodiversity is changing over the course of several years. Click here to download the data
Now that you have the data: Lets try and calculate D for the first year at the Pig Pen Site. In excel we can use the formula bar to calculate our numerator and then drag the Formula down the column to do the calculation for each species. 1.Type in = in cell C6 2.Then type in the cell B6(B6-1) 3.This will give you the calculation for 53(53-1), which is n(n-1) for your first observation. 4. Next use your mouse to grab the right corner of the cell and drag the cursor down to your last species. 5. Go to the next slide to see if your data looks the same
Now let’s add all of the numbers in column C to get the Σn(n-1), which is the numerator for D This is the total for the numerator of D
Next lets calculate the denominator This is N for the N(N-1) in the denominator of SID
In excel find a new cell and calculate N(N-1) using the formula we used in calculating the denominator You should get 6780 cell B21 below. Now lets put it all together to calculate SID for the Pig Pen site, your data should look like this In cell B22 type in the formula You want excel to calculate Remember SID= 1-Σn(n-1)/N(N-1) Thus you will need to type in: 1.= 2.(C20/B21) 3.Hit Enter 4.You should get a SID of 0.959
On your own or in a group Calculate SID for the Lower Dorsey site You can do this for each site for every year in the data set Can you see any changes in salamander diversity between the sites or over the course of several years? What can you say about the salamander population in the GSMNP?