Joseph A. Veech. 2000. A null model for detecting nonrandom patterns of species richness along spatial gradients. Ecology 81:1143-1149.


Supplements

Supplement 1: SPECIES RICHNESS/SPATIAL GRADIENT PROGRAM (SRSG).
Ecological Archives
E081-010-S1.

Author
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Description


Supplement 1: Revision 1:
Ecological Archives E081-010-S1.
Submitted 1 May 2002; Published 1 May 2002.

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Author

Joseph A. Veech
Ecology, Evolution, and Conservation Biology Program
Department of Biology
University of Nevada
Reno, Nevada 89557


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Supplement 1, original:

source.htm -- Source code
E081010.exe -- Compiled code (Visual Basic)

Supplement 1, revision 1 (1 May 2002):

read_me.txt
SRSG2.EXE
XNMBA420.DLL
XNMBA458.DLL
XNMTE420.DLL
XNMTE458.DLL


Description

This program is a null model used for testing whether a pattern of species richness along an elevational or latitudinal gradient is random or not. A specified number of null species richness curves are generated by random placement of the actual range widths (of the species being studied) along the gradient. The gradient is divided into a specified number of zones and the species richness of each zone is calculated. Species richness curves constructed in this way can then be compared to a composite species richness curve (which is an average of many independently generated species curves = the number of iterations). The comparison of each null richness curve is summarized by statistic d, the average difference between the two curves being compared. The user can also find d for a real species richness curve compared to the composite curve. Comparison of the d value for the real curve to the null d values tells the user whether or not the real curve is random.

The user inputs the range width of each species and the species richness at each point or zone along the gradient (i.e., the richness curve). The upper and lower bounds of the spatial gradient as well as the number of zones or points along the gradient are also inputted by the user. The input lines are self-explanatory.

If the dataset contains many species (more than 100) or many richness estimates or if more than one richness curve is to be tested, then the user should consider modifying the program such that the data are read into the model from a text file. For help in modifying the program contact the author.


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