names/systematics

[Doug Yanega]

James Kruse wrote:

>I await (expect) flames... but tell me what a subspecies is.

It's subjective. Among non-lepidopterist insect systematists, the concept
only seems to be applied where you have allopatric (non-overlapping)
populations with a consistent and exclusive difference - morphological,
behavioral, genetic (which, to an adherent of the Phylogenetic Species
Concept, makes them separate species) but which the taxonomist feels is
insufficient evidence that they are truly separate lineages. If there are
intermediates, then they're just variants, and if they're different and
sympatric, then they're either polymorphic forms or separate species. From
what I've seen of lep subspecies, things are looser, primarily with regards
to the differences being "consistent and exclusive". Just try identifying a
fritillary without a locality label to subspecies. If you can't ID it
reliably without knowing where it's from, then most people wouldn't
consider it a good subspecies.
        It seems that for other insect groups, subspecies are merely
reflections of a conservative systematist hedging his/her bets based on too
little information; quite likely, most of these taxa will prove to be
separate species if and when the molecular folks get down to the work of
alpha taxonomy. I wouldn't hold my breath waiting to see how many
fritillary subspecies will hold up to the same scrutiny.

>I'm not even
>sure what a species is and I consider myself a systematist (and no, I'm
>not a lone idiot. The concept of species is an active, persisting debate).
>I know all of the different definitions and associated arguments and think
>of them while looking at morphology, ecology, molecules, etc., as I think
>I should.

Most people, regardless of their practical approaches, will admit that the
patterns of gene flow within and among populations is of paramount
importance - and since natural systems can exhibit a bewildering and
unpredictable variety of patterns of gene flow, from true panmixis to
purely clonal, no one concept of "species" is ever going to accommodate for
*all* of them in a satisfactory manner. There is probably always going to
be some level of subjectivity involved in what people consider "species",
we can only try to get some sort of criteria representing a "common
ground", to weed out species concepts that are *too* subjective or
impractical.

>Consider the statements:
>-Just because it is on a different mountain top/feeds on Rhamnus/flies in
>the spring/has an orange dot/ doesn't mean it is 'different'.
>-Just because it is on a different mountain top/feeds on Rhamnus/flies in
>the spring/has an orange dot/ it must be 'different'.

That's all going to come down to the context. How far removed is that
mountaintop from the rest of the range? Geological age of last contact?
What are the normal host plants? Is the putative sister polyphagous? How
many broods are normal? Does it always have an orange dot, when no other
populations *ever* have one? It generally comes down to a question of how
much information is available. The more we have, the more confident we can
be about our decisions. If we had enough data, we wouldn't have any use for
the "subspecies" concept at all, or if we did, it would have to be
explicitly renamed as "geographic variant", since that's basically what it
serves to communicate at this point.

Peace,


Doug Yanega       Dept. of Entomology           Entomology Research Museum
Univ. of California - Riverside, Riverside, CA 92521
phone: (909) 787-4315
                http://insects.ucr.edu/staff/yanega.html
  "There are some enterprises in which a careful disorderliness
        is the true method" - Herman Melville, Moby Dick, Chap. 82