[Taxacom] [iczn-list] GENERAL CALL TO BATTLE

[Les Watling]

Yeah, I see what you are saying John. I think I didn't express things too
clearly.

Here is the main difference between dealing with morphology vs. molecular
genetics, I think. When we see differences in morphology, our experience
allows us to understand whether the difference is "small" or "large."
Admittedly subjective, but in a group that you have studied for a long time
you get a feel for the significance of the morphological differences. When
I worked with crustaceans I could make those assessments, but I also could
not say with 100% assurance that they represented different species. What I
could say, though, from samples where there were many specimens, that
certain forms occurred over and over again, with the morphology the same
down to the last detail on all appendages, depending on growth stage.
Still, it was possible that small differences, say in setation or
something, might have been variants rather than separate species, but due
to the consistency of the morphology, the variations were treated as
species differences unless proved otherwise. And, like you, I have
described new species from single specimens, usually because they were
unlike anything I had seen before. Still, they could some weird variant,
but that would need to be proved with more sampling.

So, our experience causes us to say, as Libbie Hyman once said, that "a
species is what I say it is." That's kind of tongue in cheek, but I think
closer to our reality.

Also, we know little about the genetic underpinnings of all that
morphology. Someday maybe we will get a better understanding, but for the
most part it is not likely to be one gene (except for situations like the
single regulatory gene that causes crustaceans to not express any
appendages on the abdominal somites and so become insects).  On the other
hand, a lot of genetic distinction of "species" is based on mitochondrial
genes, which have no relationship to morphology at all, and may not vary in
line with the nuclear genes that do. I suppose that is my real trouble with
using DNA sequences to define species. I am more comfortable with
morphology, because I know that the morphology I see must result from the
expressions of a large number of genes. Maybe as Rich says, some day
biologists will have worked out the relationship between gene sequences and
morphology and so then using a Star Trek type of tricorder might be a
reality.

Until then, I will stick to morphology and be skeptical of barcoding unless
it is somehow related to good morphology.

Les







Les Watling
Professor, School of Life Sciences
216 Edmondson Hall
University of Hawaii at Manoa
Honolulu, HI 96822
Ph. 808-956-8621
Cell: 808-772-9563
e-mail: watling at hawaii.edu






On Sun, Feb 14, 2021 at 3:21 PM John Grehan <calabar.john at gmail.com> wrote:

> Hi Les,
>
> Below some comments for what they are worth or not.
>
> I find this whole business of naming taxa on the basis of DNA sequences
> very disturbing. If conservationists really need some name for some
> organism that they found that has not been described they can use whatever
> designator they like.
>
> If 'whatever designator they like' then why not DNA?
>
> But they should not call those organisms with
> different barcodes new species, and name them, and expect the names to be
> Code compliant.
>
> But if I understand the discussion so far, as long as the documentation
> meets code requirements then it will be code compliant just as much as any
> morphological designation. And if not code compliant then they are just no
> code compliant. Whether they are biologically valid is of course a separate
> question.
>
> They have no idea whether they are separate species or not.
>
> But this is true of morphology as well. Just finding a morphological
> difference does not automatically biologically validate as proposed species.
>
> And anyone coming along later may or may not ever find that sequence again.
> Has anyone ever looked to see if there is a whole population of organisms
> with the same genetic sequence? How often has that been done? I suspect
> most surveys grab only a few specimens of each of the DNA "species." At
> least that is the case for the groups I know best (not insects, however).
>
> But often enough this situation is true of morphologically defined species
> where the whole population is never assessed, just a subsample, and
> sometimes just a single specimen (guilty of that myself).
>
>  We can't know unless something can be done to see whether there is
> reproductive capability with the production of viable
> offspring, etc., you know, the old biological species concept. But maybe
> that has gone out the window, too.
>
> So your view is that unless one carries out a detailed study of the
> biological circumstances and relationships among populations one should not
> propose new species. That is certainly a valid viewpoint. But there is also
> the viewpoint that such studies are usually impossible or impractical and
> so prefer to name new species nevertheless.
>
> I know that I am old-fashioned, and at the long end of my career, but I
> think the molecular folks are pushing this naming business a bit too fast.
>
> Perhaps so. I can sympathise (as one who is a morphologist taxonomist) but
> that's life sometimes.
>
>
>
>
>>