Re: NANFA-- subspecies (was fantail darters)

Bruce Stallsmith (
Sat, 22 Jan 2000 14:34:20 EST

Oh no, I'm a conservative in my old age! To me the Biological Species
Concept (only from 1942!) still works best for sexually reproducing
organisms, esp. animals.

>If they do occur in sympatry, and hybridize, then scientists
>operating under the BSC would view speciation as being incomplete.

Depending on how much "hybridizing" happens, then you would have had
isolated populations, not separate species. And talking about "evolutionary
tendencies and historical fates" implies predetermination of outcomes in a
way that would make Darwin cringe.

But, I agree, subspecies are a weak concept at best. And if we go crazy with
a Species Concept debate here, it would be almost as room-clearing as

--Bruce Stallsmith
Huntsville, AL
"Yeah, been readin' Ernst Mayr agin'."

>>>Besides, the category "subspecies" is a nonsensical term anyway, >>and
>>>no place in a classification of diversity.
>>Does it have something to do the fact that species from the same >genus
>>interbreed with each other? Does that make them so similar >genetically
>>that further breaking down into categories of subspecies >is an inaccurate
>>way to classify their relationship to each other?
>Not quite. Sorry for the jargon, there's no easy way to put this...
>If one is operating under the Evolutionary Species Concept (ESC), species
>are lineages of ancestor-descendant populations which maintain their
>identity from other such lineages and which have their own evolutionary
>tendencies and historical fate (Wiley 1978). Due to the fact that species
>are "individuals", rather than "classes", they cannot be defined, only
>described or diagnosed. Species diagnoses are based on characters unique
>a lineage, which are termed autapomorphies.
>The category "subspecies" has been used by some taxonomists (more
>in the past, and within certain groups [birds, herps]) as a category of
>convenience to delineate populations which are unique, and diagnosable, but
>which they don't "feel" warrant "species status." This is often an
>decision based on some sort of hypothesized introgression or purported
>hybridization. Under the flawed Biological Species Concept (BSC), species
>status is dependent on the attainment of reproductive isolation. With
>allopatric species (where a larger population is subdivided by a vicariance
>event, and the two populations differentiate), this is not "tested" until
>the two populations are reexposed to each other. This is absurd! Since
>allopatric speciation is hypothesized to be the primary means of
>diversification, if you can't test species boundaries, you've got a real
>problem. If they do occur in sympatry, and hybridize, then scientists
>operating under the BSC would view speciation as being incomplete.
>Why is this a problem? Well, if the supposedly interbreeding populations
>not sister taxa (more closely related to each other than to anything else),
>then the lack of reproductive isolating mechanisms is a moot point!
>Without a phylogenetic analysis to determine the relationships within
>the populations/species, there's no way to identify sister taxa. The large
>number of subspecies we have now are a reflection of a prior way of doing
>systematics, one which is slowly being replaced as we gain data on various
>groups of organisms...and as old taxonomists retire!
>I hope this helps clarify the matter.

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