This is something that frequently comes up in the CvE debates -- that evolution necessarily increases diversity (creationist) versus diversity is a result of evolution and can fluctuate (evolutionist).
The first problem is how to define (biological) "diversity" ...
Fairly obviously we would use the second definition.
If we take it to it's extreme it would mean each individual organism differs from all others, so the sum total of all organisms would be the total diversity at any one time. The problem here is that there is ongoing death and ongoing birth, and the total numbers do not change significantly except in times of major extinctions.
If we limit it to species (per example in the definition), then diversity would be measured by the sum total of all species at any one time. Again, the problem is that species are born and die, and the total numbers do not change significantly except in times of major extinctions.
Either way the concept can be quantified (although actual measurement could be extremely difficult), so the increase or decrease over time could be measured and compared.
That an individual organism or a species can die at any time shows that diversity does not always increase due to evolution (mutation and natural selection processes).
Evolution is the change in hereditary traits in populations from generation to generation, and this results in diversity when species are born or in loss of diversity when species die. The diversity we see is the result of evolution, but it is not a necessary result.
What this data can tell us is whether more or less species are being developed vs going extinct. This in term may inform debates on whether global warming or the impact on man on the environment is having an effect on biological life and the diversity of life as we know it.
But I don't see it as being a critical factor in the study of biology or evolution.
This is an interesting topic for me personally, but I can't really see what it is you want to debate. Is there a question in there somewhere? Where do you want/intend to go with this topic?
This came up in debate with MurkyWaters regarding the definition of the theory of evolution, and it seemed a puzzle to me why he was so intent on it (other than to try and make the definition as impossible as possible).
I guess the questions are: am I missing something? Do creationists see this differently? Is there some tie-in to "macro"evolution?
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