[Taxacom] Reproducibility of descriptive data

[Gurcharan Singh]

I am happy that you agreed: morphologica gaps are important (behavioural 
gaps are unimportant alone) for the sake of practical taxonomy. You just 
plant two trees in the garden with no obvious external distinction, and 
write a label they are reproductively isolated. Taxonomy gets meaningless 
for us and the common people who have to use these plants, if we don't have 
means to tell them: how do we differentiate them. Theories are always 
fascinating, but they should be practical. Then only they are relevant.

Dr. Gurcharan Singh
Associate Professor
SGTB Khalsa College
University of Delhi, Delhi
India
http://people.du.ac.in/~singhg45
----- Original Message ----- 
From: "Stephen Thorpe" <s.thorpe at auckland.ac.nz>
To: "Gurcharan Singh" <singhg at sify.com>; "Mary Barkworth" 
<Mary at biology.usu.edu>; "TAXACOM" <taxacom at mailman.nhm.ku.edu>
Sent: Thursday, September 10, 2009 7:59 AM
Subject: RE: [Taxacom] Reproducibility of descriptive data


[G. Singh said] otherwise a student comes to me ask the name of species, and 
I tell him: let me first try to breed it with specimen B and determine if 
they are two distinct species
[reply] this is a caricature! You don't "try to breed it with specimen B and 
determine if they are two distinct species"! Instead you hypothesise if the 
morphological/behavioural gaps are wide enough to ensure "reproductive 
integrity" if they came together under natural conditions ...

Apomicts present different problems altogether ...

Stephen

________________________________________
From: Gurcharan Singh [singhg at sify.com]
Sent: Thursday, 10 September 2009 1:21 p.m.
To: Stephen Thorpe; Mary Barkworth; TAXACOM
Subject: Re: [Taxacom] Reproducibility of descriptive data

I wish we are more realistic about species identity. Evolutionary species
concept, to me is the most realistic approach: The species should be able to
maintain its identity through generation. It is understandable to talk of
reproductive bariers in sexually reproducing organisms, but what about
apomicts?. What about vicariants? no one thinks of merging Platanus
orientalis and P. occidentalis. The moot point is, especially in plants that
species should be remain distinct, and more important than that there should
be some identifiable features in each species, otherwise a student comes to
me ask the name of species, and I tell him: let me first try to breed it
with specimen B and determine if they are twop distinct species.


Dr. Gurcharan Singh
Associate Professor
SGTB Khalsa College
University of Delhi, Delhi
India
http://people.du.ac.in/~singhg45
----- Original Message -----
From: "Stephen Thorpe" <s.thorpe at auckland.ac.nz>
To: "Mary Barkworth" <Mary at biology.usu.edu>; "TAXACOM"
<taxacom at mailman.nhm.ku.edu>
Sent: Thursday, September 10, 2009 5:10 AM
Subject: Re: [Taxacom] Reproducibility of descriptive data


> >So how often do they have to interbreed and produce how fertile an
> >offspring?
>
> This is a difficult question, but that doesn't mean that it doesn't have
> an answer! Analogy: Australia (forget Tasmania and smaller islands) has
> natural boundaries (unlike U.S.A.), but the boundaries are somewhat fuzzy
> (or "swooshy": the tide goes in and out). So the answer to your question
> isn't necessarily perfectly precise either. Nevertheless, there is a BIG
> difference between species (Australia) and genera (U.S.A.)
>
>
>>And what if the isolating mechanism is the Atlantic Ocean - only then some
>>foolish biped comes along, brings two things together than were once very
>>effectively isolated by the ocean and find they are interfertile! Does
>>that negate the impact of the accumulation of other genetic differences
>>between them?
>
> If they haven't diverged enough to maintain "reproductive integrity" [what
> a quaint term!] when brought together under natural conditions, then they
> aren't distinct species! It doesn't negate the genetic differences between
> them, it just means the differences are not significant enough to count as
> distinct species...
>
>
> ________________________________________
> From: Mary Barkworth [Mary at biology.usu.edu]
> Sent: Thursday, 10 September 2009 11:18 a.m.
> To: Stephen Thorpe; TAXACOM
> Subject: RE: [Taxacom] Reproducibility of descriptive data
>
> So how often do they have to interbreed and produce how fertile an
> offspring? And what if the isolating mechanism is the Atlantic Ocean -
> only then some foolish biped comes along, brings two things together
> than were once very effectively isolated by the ocean and find they are
> interfertile! Does that negate the impact of the accumulation of other
> genetic differences between them?
> Mary
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