species recognition

John Grehan jrg13 at psu.edu
Fri Jun 11 08:09:49 EDT 1999

>In theory (!) there is a good system to recognize species or subspecies
>among contiguous populations. Look at the single mate recognition systems
>(smrs of Patterson) in both populations. 

mate recognition systems are good examples of essentialist thinking. The
belief seems to be that species are able to recognize each other, so
where recognition takes place the individuals are the same species
(perhaps oversimplistic, but anyone is welcome to pick up on that).
But when a wasp mates with an orchid, it seems to recognize the 
plant as a mate - despite the obvious problem with that. Mate
recognition is just the other side of the biological species definition.

They may be secondary sexual characters,
>behaviors or androconia and Bernardi (among others) has shown that
>in really contiguous or overlapping populations, these systems evolved in
a way
>to produce strong isolating barriers, whereas these barriers may not exist in
>isolated populations. 

It is also possible that these systems evolved in a way to RESULT in
strong isolating barriers (instead of to - which is teleological).

If these barriers exist, the two populations should belong
>different species.
>Frequently, species A won't mate with species B in contiguous populations
>forced matings (artificial pairing with hand in the case of leps) will
>offspring. On the other hand, species A will mate with (geographically
>C without 'help', resulting in sterile mating.

This shows the complexity of mating relationships. In the process of
it is apparent that interbreeding of individuals generally becomes less
but this is part of the process of differentiation, not its defining
essence. By 
treating species as individuals, characteristics such as mate recognition 
may be included among the criteria to assess differentiation, but only as one
of the biological characters used in a diagnosis involving a particular
place and time. The conclusion may be reached, for example, that two
species interbreed 
at part of their range and not others, or under different circumstances. So
is "recognition" under a particular set of conditions, and no recognition
under others.

My view is that species are real, but because they are phylogenetic
there is no recipie for their recognition - they have to be diagnosed in
to particular biological (including breeding relationships, behaviour,
morphology) and geographic characters.

John Grehan

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