[Taxacom] Biodiversity and Species Value

[Michael Heads]

Hi Stephen and Doug,
 
Taxononomic rank isn't bad as a rough estimate of biodiversity, but not all species  represent equal biodiversity and so an old, distinctive species in one group may represent more biodiversity than a family in another, oversplit group. Phylogenetic diversity has been measured using numbers of species in the sister group, so e.g. Amborella the basal angiosperm on  New Caledonia would be ranked higher than Acanthisittidae the basal passerines on New Zealand, because there are more angiosperm species than passerine species. Again, this assumes that all species represent equal biodiversity. The other main school suggests using branch length, so a group with long brach length or more synapomorphies would rank more highly. But this obscures the importance of basal groups with few synapomorphies.     
 
Michael Heads

Wellington, New Zealand.

My papers on biogeography are at: http://tiny.cc/RiUE0

--- On Fri, 11/6/10, Stephen Thorpe <stephen_thorpe at yahoo.co.nz> wrote:


From: Stephen Thorpe <stephen_thorpe at yahoo.co.nz>
Subject: Re: [Taxacom] Biodiversity and Species Value
To: "Doug Yanega" <dyanega at ucr.edu>, TAXACOM at MAILMAN.NHM.KU.EDU
Received: Friday, 11 June, 2010, 10:49 AM


sounds like you think all species are of equal "value", but surely one species of a megadiverse genus is far less important than a monotypic family? Why conserve just species? Why not all taxa? The higher the taxon, the more important it is. So a family going extinct is far more of a tragedy than just some species ...




________________________________
From: Doug Yanega <dyanega at ucr.edu>
To: TAXACOM at MAILMAN.NHM.KU.EDU
Sent: Fri, 11 June, 2010 10:41:00 AM
Subject: Re: [Taxacom] Biodiversity and Species Value

Steve Manning wrote:

>Yes, my main point though is that the NUMBER of species in a place is
>more important than going to huge lengths to conserve one or a few
>particular species no matter where they are, so at present reliable
>estimates of the approximate NUMBER of species is more important than
>info. on their relationships, anatomy, genetics or even on their
>interactions.  Hence a higher priority to preserving tropical rain
>forest areas, even if poorly known in details, than a particular
>species of bird or bat that might be threatened there or anywhere
>else if other unknown species perish while we are focused on the
>"charismatic" species at their expense.

Were I magically empowered with the ability to influence such 
decisions, pure species numbers would be fairly low on my list of 
criteria when ranking habitats' conservation value, their 
phylogenetic affinities even lower, and charisma would not factor in 
at all. I consider the limits of a species' distribution to be of 
primary importance; as the area of the planet a species occupies 
shrinks, the conservation value of the shrinking area goes up 
accordingly. A species known from a single spot, like the Devil's 
Hole Pupfish, confers an *immense* value upon the area it resides in, 
even though that habitat (Ash Meadows wildlife refuge, in this case) 
has nowhere near the total species diversity of anywhere in the 
tropics. However, Ash Meadows has a whole PILE of endemic plants and 
animals, and each one of those counts for a LOT. Various caves across 
the globe are incredibly species-poor, but a lot of them contain 
endemic species - just counting taxa, or charisma, would mean that 
virtually none of these habitats would ever be protected.

Ultimately, I see the rationale for conservation as boiling down to 
this: "How likely is it that something will go extinct if we don't 
protect the integrity of this particular place?" - meaning something 
like endemicity really needs to be a major consideration.

Sincerely,
-- 

Doug Yanega        Dept. of Entomology        Entomology Research Museum
Univ. of California, Riverside, CA 92521-0314        skype: dyanega
phone: (951) 827-4315 (standard disclaimer: opinions are mine, not UCR's)
              http://cache.ucr.edu/~heraty/yanega.html
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82

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