[Taxacom] Heritage biodiversity

Bob Mesibov mesibov at southcom.com.au
Thu Jul 20 20:59:47 CDT 2006

Pierre Deleporte is certainly correct in saying that some species are 
favoured for conservation for "intuitive" reasons which are not always 
clearly stated. Because different people have different ways of valuing 
biodiversity, there will always be disagreement about which species should 
have conservation priority. I fully agree with Pierre (and others) that the 
most realistic approach is to conserve as many different landscapes in as 
many different places as possible, and that species-level conservation (with 
its disagreements) should only complement this broader aim.

Getting back to Arthur Chapman's posts, the following rather terrifying 
quote is from Witte, J.P.M. 1998. National Water Management and the Value of 
Nature. Doctoral thesis, Wageningen Agricultural University, Netherlands 
(ISBN 90-5485-831-1), p. 153:

"Anyone who has ever joined a field trip of biologists knows how nature is 
generally valued: on the basis of rarity. During field trips it is quite 
common to see a biologist kneel to the ground, searching for some rare 
plant... Botanists uprooting some rare plant species even justify their 
action with the phrase: 'whatever is rare should remain rare'. In other 
words, it does not matter if one individual disappears, because the value of 
the remaining individuals will increase and, with that, the _total_ value of 
the _species_ remains unaltered."

Witte noted how the conservation value of individual species in the 
Netherlands could change in a short time as the species became more or less 
widespread and abundant, which is another reason he equates rarity and 
value. (For an excellent article on the objective measurement of rarity, see 
e.g. Witte, J.-P. M. and Torfs, J. J. F. 2003. Scale dependency and fractal 
dimension of rarity.  Ecography 26: 60–68.)

On 8 June 2006, Nature published a report on the rediscovery of a California 
millipede, Illacme plenipes, with the largest known number of legs. The news 
was widely circulated in the popular science media because the high number 
of legs makes this species _exceptional_. The rediscoverers, however, say 
"Because of the rarity and narrow geographical range of this delicate 
species, its fragile habitat must be protected at all costs." The 
re-collection locality was generalised to "San Benito County".

Without going into details, the authors also mentioned that the taxon to 
which I. plenipes belongs, Siphonorhinidae, is special: it consists of a few 
monotypic genera with disjunct distributions. Thus the conservation value of 
this species has at least 4 elements: it's morphologically unusual, it's 
geographically restricted, it's very hard to find (rare in the abundance 
sense) and it's phylogenetically isolated.

Thus I. plenipes is a model species for complementing landscape 
conservation, as Pierre Deleporte suggests. Unfortunately it suffers a 
crippling disadvantage in the global conservation race. It's an 
Dr Robert Mesibov
Honorary Research Associate, Queen Victoria Museum and Art Gallery
and School of Zoology, University of Tasmania
Home contact: PO Box 101, Penguin, Tasmania, Australia 7316
(03) 64371195; 61 3 64371195

Tasmanian Multipedes
Spatial data basics for Tasmania

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