Rarity

[Doug Yanega]

Craig Hilton-Taylor wrote:

>Gaston argues for the adoption of a standard definition
>which is simple and broadly applicable. He suggests classifying 25%
>of species in any assemblage with the lowest abundances or smallest
>range sizes as rare, regardless of how the parameters of abundance
>and range size are measured.
>
>Any comments?

This would appear to still leave things tremendously ambiguous - which is
more important, abundance or range size? Large mammals may have extremely
low abundances but huge range sizes, and many insects may have high
abundance but incredibly tiny range sizes. Does Gaston give a formula for
combining these two parameters into a single scalar (in order to designate
the 25% which are "rare"), or is this as confusing as it appears? This
wouldn't appear to resolve the dilemma that's been the heart of this
thread.

Sincerely,

Doug Yanega    Depto. de Biologia Geral, Instituto de Ciencias Biologicas,
Univ. Fed. de Minas Gerais, Cx.P. 486, 30.161-970 Belo Horizonte, MG   BRAZIL
phone: 031-448-1223, fax: 031-44-5481  (from U.S., prefix 011-55)
                  http://www.icb.ufmg.br/~dyanega/
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82