[Taxacom] barcode of life

Stephen Thorpe stephen_thorpe at yahoo.co.nz
Thu Jul 1 17:32:00 CDT 2010


what Robin says is more or less along the right lines, but to be a trifle clearer:

species boundaries delimit reproductive isolation (which is not to say that it is black and white, all or nothing) and to that extent are "real"

boundaries for higher taxa are arbitrary/subjective/conventional, and delimit nothing "real" in the world (which is not to say that the taxa themselves are purely arbitrary/subjective/conventional, only that their boundaries are - the boundaries must delimit monophyletic groups)

of course, the requirement of reproductive isolation is implicit in just about every notion of species - what sense can be made of sympatric cryptic species if they freely interbreed? Total nonsense!




________________________________
From: Robin Leech <releech at telusplanet.net>
To: Stephen Thorpe <stephen_thorpe at yahoo.co.nz>; dipteryx at freeler.nl; taxacom at mailman.nhm.ku.edu; Steve Manning <sdmanning at asub.edu>
Sent: Fri, 2 July, 2010 2:52:44 AM
Subject: Re: [Taxacom] barcode of life

Hi Steve,
The possible reason is that species are real, and that all categories from
genera on up the hierarchy represent human imagination.
Robin

----- Original Message ----- 
From: "Steve Manning" <sdmanning at asub.edu>
To: "Stephen Thorpe" <stephen_thorpe at yahoo.co.nz>; <dipteryx at freeler.nl>; 
<taxacom at mailman.nhm.ku.edu>
Sent: Thursday, July 01, 2010 8:43 AM
Subject: Re: [Taxacom] barcode of life


> It is interesting that I have not detected anywhere near as much
> controversy or discussion about delimitation of Genera, Families, and
> other taxa more general in the hierarchy than species - yet surely
> there has to be even less precision possible in defining their
> boundaries than those of species(?).
>
> Steve
>
> At 02:52 AM 7/1/2010, Stephen Thorpe wrote:
>> >better to leave religion out of it and keep it simple
>>
>>but it ain't simple either way!
>>
>> >but this leads to all the different beliefs on what constitutes
>> "reproductive isolation" ...
>>
>>this is the point that nobody gets! You have to consider two cases,
>>viz. the "in practice" case, and the "theoretical basis" case which
>>underpins it
>>
>>In practice, there is less disagreement about what constitutes
>>reproductive isolation than there would be if every faction could
>>just have their own species to suit themselves. In other words,
>>reproductive isolation "works". It isn't perfectly precise and
>>objective, but I bet (at least) 9 times out of 10 when two
>>taxonomists just consider reproductive isolation as a criterion,
>>they will agree on species boundaries. Most disagreement seems to
>>arise from differing "species concepts" (i.e., biological,
>>morphological, phylogenetic, etc.)
>>
>>The theoretical basis which underpins this goes something like this:
>>take topography as an example. It describes a real objective feature
>>of the world, yet there are different altitudes, and the contour map
>>will be different for each choice of altitude. But this "dimensional
>>aspect" doesn't imply subjectivity. Similarly, choose whatever level
>>of reproductive isolation you like and draw the species boundaries
>>for that choice. This will also describe a real objective feature of
>>the world. In practice we cannot measure reproductive isolation very
>>precisely at all, but luckily in most cases the result will be the
>>same for a wide range of choices that would cover most peoples idea
>>of the appropriate level for drawing the map. Of course there will
>>be some problem cases, but by and large I suggest there would be
>>more agreement than doing it any other way ...
>>
>>Stephen
>>
>>PS: If we accept "Pylean subjectivity", then we cannot criticise
>>molecular taxonomists for describing cryptic species to suit
>>themselves, as it is none of our concern. We just have to ignore
>>them, and do it our way. I don't know quite where this would leave
>>global biodiversity databases like EoL, etc.? Maybe we need one for
>>the molecular species, one for the biological species, one for the
>>morphological species, one for the phylogenetic species, etc....
>>
>>
>>
>>________________________________
>>From: "dipteryx at freeler.nl" <dipteryx at freeler.nl>
>>To: taxacom at mailman.nhm.ku.edu
>>Sent: Thu, 1 July, 2010 7:21:57 PM
>>Subject: Re: [Taxacom] barcode of life
>>
>>Van: taxacom-bounces at mailman.nhm.ku.edu namens Stephen Thorpe
>>Verzonden: do 1-7-2010 7:03
>>
>> > but this leads to different factions of "the community"
>> > (=different communities) with their own species
>>
>> > better to try to hold on to reproductive isolation
>> > as the one true canonical criterion of species boundaries ...
>>
>>***
>>but this leads to all the different beliefs on what constitutes
>>"reproductive isolation" ...
>>
>>better to leave religion out of it and keep it simple.
>>
>>Paul
>>_______________________________________________
>>
>>Taxacom Mailing List
>>Taxacom at mailman.nhm.ku.edu
>>http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
>>
>>The Taxacom archive going back to 1992 may be searched with either
>>of these methods:
>>
>>(1) http://taxacom.markmail.org
>>
>>Or (2) a Google search specified
>>as:  site:mailman.nhm.ku.edu/pipermail/taxacom  your search terms here
>>
>>
>>
>>
>>_______________________________________________
>>
>>Taxacom Mailing List
>>Taxacom at mailman.nhm.ku.edu
>>http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
>>
>>The Taxacom archive going back to 1992 may be searched with either
>>of these methods:
>>
>>(1) http://taxacom.markmail.org
>>
>>Or (2) a Google search specified
>>as:  site:mailman.nhm.ku.edu/pipermail/taxacom  your search terms here
>
>
>
>
> _______________________________________________
>
> Taxacom Mailing List
> Taxacom at mailman.nhm.ku.edu
> http://mailman.nhm.ku.edu/mailman/listinfo/taxacom
>
> The Taxacom archive going back to 1992 may be searched with either of 
> these methods:
>
> (1) http://taxacom.markmail.org
>
> Or (2) a Google search specified as: 
> site:mailman.nhm.ku.edu/pipermail/taxacom  your search terms here
> 


      


More information about the Taxacom mailing list