Re: Species [arbitrary to a degree]

[Randy King <randyk@ims.com>]

Doesn't the same problem (ring species) occur in evolution.  That would seem to 
be a critical
problem when you identify species with only a vague idea of where in time they 
belong.  As an
animal evolves through time you get an extreme case of the species problem.  
Its been addressed
in that context, with no resolution to my knowledge.  

I'm not sure I see the relvance of the argument below, regarding a ring species 
as two distinct
species.  Maybe I'm missing something.  But the problem that I see is that you 
require a fuzzy
line to separate the species.  The ring species could be regarded as a single 
species or multiple
depending on the context, this makes it difficult to use the term with any 
relevance.  I think I'm
falling into the camp that the species concept isn't useful as its defined.  

<...However, I think it is even more of a mistake to so quickly dismiss the 
important implications
>of "ring species" where populations (e.g., subspecies) can interbreed with 
>adjacent populations
>just fine, until the species circles around (circumpolar, around a mountain 
>range or whatever),
>and the populations at the end of the ring can no longer interbreed at all.  
>I've always regarded
>the ring species as a prime example of the "fuzziness" of the boundaries 
>between species "in
>space".  Throw in the fourth dimension and the fuzziness gets even worse 
>(which makes 
>paleontological species all the more controversial and difficult).>
>
>  What I feel is being regarded here is the problem with adapting a physical 
> species concept and a
>genetic species concept, to each other. Many sparrows in Eurasia form ring 
>species, in as much as
>a series of populations seem to be more genetically compatible as they come 
>closer to each other.
>Those populations which was most polar are genetically isolated. This is the 
>specific grey area.
>Once genetic isolation has come into play, one does not get a paraphyly, but a 
>split. The remnants
>(the populations still in the middle) are an example of either 1) the basic 
>population, or
>original genetic type or 2) a hybridization of the two parallel species. Since 
>it would require
>phylogenetic testing of the two distinct polar populations to determine the 
>origin, the statement
>that there are two species at work here would be assumptive at best.