Biodiversity Part II

1
Biodiversity Part II

• The National Institute for Mathematical and
  Biological Synthesis

2
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.

3
First lets take a look at the data
4
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.

5
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

6
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.
• Type in in cell C6
• Then type in the cell B6(B6-1)
• 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

7
Now lets add all of the numbers in column C to
get the Sn(n-1), which is the numerator for D
?
This is the total for the numerator of D
8
Next lets calculate the denominator
?
This is N for the N(N-1) in the denominator of SID
9
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-Sn(n-1)/N(N-1)
• Thus you will need to type in
• (C20/B21)
• Hit Enter
• You should get a SID of 0.959

10
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?