Re: NANFA-L-- Diversity Indicies

dlmcneely at
Thu, 29 Sep 2005 12:22:45 -0500

Todd, a part of the concern, if I read into what you are saying
correctly, is that you want to be able to use diversity as an analogue
of something valuable but not defined. Or am I all wet? Because in the
mathematical sense, yes, the second sample you described is more
diverse, due to its very high evenness. Intuitively, we seem to see
(I'm included) highly speciose samples as more diverse than their
opposites. But that is richness, not diversity, that we're seeing.
But you already knew that, which may be part of your frustration.

If you are looking for a way to quantify your as yet unnamed and
undefined value, then maybe diversity is not what you are after.

Some workers have sorted fishes into "tolerant," and "intolerant"
(sometimes with finer scale sorting) w/respect to pollutants, habitat
degradation, and so on, without defining an index. Perhaps some sort
of system that would count the number of individuals in various
tolerance categories would serve your purpose? My advisor once told me
that the greatest success of a graduate student was to develop
something novel that was useful to other workers. Master's students
have "succeeded" that way.

One difficulty of using any of the indices that have been developed to
infer something about habitat quality (and you may have no intention of
or desire to do so) is that some habitats, like headsprings, desert
streams, and so on are naturally undiverse, both w/respect to
patchiness/environmental quality and biotically. So a low value on one
of these indices may say nothing about the condition of the system.

I know, you didn't ask all this, and the list probably isn't interested.

Have fun!


David L. McNeely, Ph.D., Professor of Biology
Langston University; P.O. Box 1500
Langston, OK 73050; email: dlmcneely at
telephone: (405) 466-6025; fax: 405) 466-3307
home page

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