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BugsMCR:

Calculate MCR for the samples at a site
Calculate MCR for all species at a site
Predict species presence from samples
BugsMCR output files explained
The variables explained

 

The MCR (Mutual Climatic Range) method is a technique for deriving quantitative temperature reconstruction from fossil beetle remains developed during the 1980's (Atkinson et al. 1986). It is a Modern Analogue Technique (MAT) in that it uses the modern thermal distribution of taxa as the basis for 'retrodicting' palaeotemperatures.

BugsCEP includes the facility for running these calculations and outputting the results in table and graph form to MS Excel, along with the sample thermal envelopes (climate space maps). The MCR component is called BugsMCR, and uses the Birmingham RECON dataset.

 

MCR uses the area of mutual overlap of the thermal envelopes of the species in a sample as the most probable thermal range, rather than looking for similar species assemblages from the presnt day.

More information about the use of MCR in Bugs can be found at http://www.bugs2000.org/bugsmcr/index.html or in Buckland & Buckland (2002).

Although it has its weaknesses, the (uncalibrated) MCR method is robust, honest in its range estimates, and mathematically transparent. It was also the first method to highlight the rapidity of warming at the end of the last Ice Age.

 

Calculate MCR for a site

MCR can be calculated for any site that includes species that have temperature data. At the time of writing there are 436 of these - you can see the list by clicking the 'Show All MCR Species' link on the BugsMCR interface.

  1. To open the BugsMCR interface click the [BugsMCR] button on the main toolbar.
  2. If you have created a site, and entered abundance data for it then it will be available from the 'Site' dropdown box towards the top of the screen. (Use the [Refresh sites list] button if it is not there).
    Sites without abundance data are not shown.
    (You can limit the species available for species list creation to only those with MCR data in the 'Species List Editor' if necessary)
  3. If the site has more than one countsheet, then selecct the required one from the 'Select Countsheet' dropdown box.
  4. Click [Activate this countsheet], and the species list will be loaded into the right hand half of the screen.
    You can now use the 'Show Current Countsheet' link to examine the abundances if you wish. Note that until you click the [Activate this countsheet] button this link will show the previously used countsheet.
  1. Select the options for output and calculation as follows:
    • Closest to 100% - calculates MCR even for samples with no 100% overlap between species.
    • TMax & TMin Graphs - create graphical output.
    • Sample envelopes - output grids of combined thermal envelopes for each sample.
    • Sample species lists - output the species list for each sample underneath their respective envelopes.
  1. Click the [Run MCR on All Samples] button, and choose a location and filename to save your output files. If 'Sample envelopes' have been selected for output these will be saved in a second file with the suffix '-matrices'.
  2. Stand back and let BugsMCR do its calculations. Wait until the Penguin has finished moving before doing anything, as the program needs full control of your computer.
  3. When calculations are complete you will be informed of where the output files have been saved, and can click on buttons to open them from within BugsMCR.
    See below for an explanation of the files.

 

Calculate MCR for all species at a site (full species list - ignore samples)

This is most useful for teaching excercises, but allows you to see the combined climatic implications of all species through series of samples.
Remember that MCR results CANNOT BE AVERAGED OVER SAMPLES*. Be creative with countsheets in order to combine samples and calculate results over several samples.

Follow the instructions above, but at number 6 click [Run MCR on Species List only].
Graphs will not be created, since only one set of results will be produced.

 

Predict species presence from temperature values

An exploratory tool that lets you (A) pick the thermal range maximums of any species, and ask the database which species can theoretically survive within those limits. You can also (B) input single summer & winter temperature values and get a list of all species that can survive at that temperature.

NOTE: The prediction tools are still under development, and the implications of the reults must be considered carefully when used. More range based search functions will be added in the near future.

(A) Use ranges

  1. Access the Predictions interface from the BugsMCR screen by clicking the [Predictions] button.
  2. Use the 'Tools' section to select a taxon from the MCR database.
  3. Click the [Copy to ranges search boxes] and the temperature values will appear in the 'Ranges' section.
  4. Click the [Find Species that are equal or narrower within range] to do what the button says.
  5. You can adjust any value and click the latter button again to see the changes. It is wise to use the TMax/TMin values and TRange values mutually exclusively, as they are interrelated. Blanking a values leaves it out of the criteria.
  6. The results will be displayed in tabular form (as a query result). You may have to move windows and resize columns to see everything at once.

For example:



Raise the upper limits of the mean summer and winter temperatures (TMaxHi and TMinHi) by 2 degrees and the species list expands as the ranges of new species are encompassed:

 

(B) Use single summer and winter values

  1. Enter a TMax and TMin value in the 'Specifics' boxes and click the [Find Species where range includes these values].
  2. These lists will be considerably larger where values close to European means are used.

 

BugsMCR output files explained

BugsMCR creates two output files on demand:
- the main file (your filename.xls) - containing results tabulation and graphs
- the matrices files (your filename_matricies.xls) - containing climate space maps and sample species lists

The Main File

Two worksheets: Graphs and Results

Graphs  

Vertical axes:
Temperature values in degrees Celcius

Horizontal axes:
Sample names

Bars:
show range of temperature values reconstructed. Note: this is a range and not a mean and s.d. - it has no valid mid-point.

Samples are currently only sorted in order of input (sorry), so may need to be rearranged on the Results worksheet.

Results  

See below for explanation of variables.

Sample:
Sample names

NSPEC:
Number of taxa in reconstruction

Overlap:
Percentage of species in sample in area of maximum overlap. Numbers below 100% are not true MCR values and should be investigated as to their ecological/taphonomic cause...


The Matrices File
Results worksheet duplicated (as above) and then one worksheet per sample.
Example sample worksheet  

Value in each cell shows the percentage of species in sample that can survive in that climate cell.

Cell indices represent the upper limits of 1 Celcius thermal cells.

Rows = TMax:
Row 1 = 36C
Row 36= 1C

Columns = TRange:
Column A = 6C
Column BH= 65C

Note: this matrx has been colour shaded with Poptools for clarity.

Sample species lists are inserted immediately below the envelopes if requested.

 

The variables explained


TMax - mean value of warmest month (usually July)

TMaxHi - highest temperature of TMax in species envelope

TMaxLo - lowest temperature of TMax in species envelope

TMin - mean value of coldest month (usually January)

TMinHi - highest temperature of TMin in species envelope

TMinLo - lowest temperature of TMin in species envelope

TRange - difference between TMax and TMin, and a useful index of continentality (higher values represent more continental climates)

TRangeHi - highest value of TRange in species envelope

TRangeLo - lowest value of TRange in species envelope

Since the thermal envelopes are grids of TMax vs TRange, it follows that TMin is calculated from the values resulting from the overlap of these grids. TMin is derived by subtracting the TRange value from TMax of each cell in the area of maximum overlap, and the extremes providing the TMinHi and TMinLo values. (Note that it is incorrect to only use the ordinally outermost cells due to the none rectangular form of the thermal envelopes).

 

 

*Notes

The area of mutual overlap for the species in two different samples will most probably not be the same as the average of the MCR results from each sample. Or, more accurately, the area of mutual overlap for the combined species lists will not be the same of the average values of the areas of mutual overlap for the separate species lists.

 

References

ATKINSON, T. C., T. C., BRIFFA, K. R., COOPE, G. R., JOACHIM, J. M. & PERRY, D. W. (1986) Climatic calibration of coleopteran data. In B. E. Berglund (ed.) Handbook of Holocene Palaeoecology and Palaeohydrology, 851-858. J. Wiley & Son, Chichester.

BUCKLAND, P.I. & BUCKLAND, P.C. (2002). "How can a database full of Bugs help reconstruct the climate?". In Burenhult, G & Arvidsson, J (eds) Archaeological Informatics - Pushing the Envelope - CAA 2001 - Computer Applications and Quantitative Methods in Archaeology, Proceedings of the 29th Conference, Gotland, April 2001. BAR International Series 1016. pp.453-461.

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Last edited:
October 15, 2006