Ratio of valid to invalid

[Andrew K. Rindsberg]

Dear Taxonomists,

Thank you for the several replies, most of them sent privately, about the
ratios of valid and invalid names (or words to that effect, given that terms
differ between botanists and zoologists).

I have heard (where and when, I no longer recall) that the average number of
accepted species per genus tends to be about 3, and that the ratio of
synonyms (and other unused names) to accepted names is about 2 to 1, so that
the number of valid names would be about 1 in 3 of the names ever proposed.
Two "rules of three". Obviously the ratios vary quite a lot from group to
group; for instance, the number of ant species in genus Attus is enormous.

What I would really like to know may be unanswerable. Are these "rules of
three" correct? If so, to what degree do they reflect evolutionary
tendencies, and would we have the same ratios in the Cambrian as today? To
what degree are the ratios affected by the way people think about categories
rather than the way nature itself is organized? Is three a "convenient"
number of subcategories, beyond which we need another splitting of
categories for efficient recall? And so on. I'm currently coordinating the
revision of the trace-fossil volume of the "Treatise on Invertebrate
Paleontology", and for ichnotaxa I suspect that the human factor is
paramount, but pretty clearly this can't be so for Attus.

I've been receiving various answers from different people on this subject,
mostly by private email, and will try to compile them later for Taxacom.
Thanks again for your help. Further replies would be much appreciated
whether public or private.

All the best,

Andrew K. Rindsberg

Geological Survey of Alabama
P.O. Box 869999
Tuscaloosa, AL 35486-6999 USA