[Taxacom] barcode of life

Robin Leech releech at telusplanet.net
Thu Jul 1 09:52:44 CDT 2010


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
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