[Taxacom] Drosophila melanogaster name change?

Richard Zander Richard.Zander at mobot.org
Tue Apr 13 11:17:06 CDT 2010


Kim:

I read way too much agreement (about paraphyly, survival of ancestors
after speciation, robust taxa, phylogenetics not being the end-all) in
what you say. Are you a member of the Post-Phylogenetic Systematics
Society? Have you been taught the secret hand-shake? Have you paid your
(nominal) dues? 

 

I largely disagree that different genetics make different taxa. I think
that different evolutionary directions are, yes, mediated by genetics,
but different genetics do not necessarily, or even usually, imply
speciation processes. We need more information about evolution than the
genetic element.

R.

 

*****************************

Richard H. Zander 

Voice: 314-577-0276

Missouri Botanical Garden

PO Box 299

St. Louis, MO 63166-0299 USA

richard.zander at mobot.org

Web sites: http://www.mobot.org/plantscience/resbot/

and http://www.mobot.org/plantscience/bfna/bfnamenu.htm

Modern Evolutionary Systematics Web site:

http://www.mobot.org/plantscience/resbot/21EvSy.htm

*****************************

 

 

-----Original Message-----
From: taxacom-bounces at mailman.nhm.ku.edu
[mailto:taxacom-bounces at mailman.nhm.ku.edu] On Behalf Of Kim van der
Linde
Sent: Tuesday, April 13, 2010 9:29 AM
To: taxacom at mailman.nhm.ku.edu
Subject: Re: [Taxacom] Drosophila melanogaster name change?

 

Hi Richard,

 

On 4/10/2010 5:19 PM, Richard Zander wrote:

> Regarding the paraphyly of Drosophila, the diagrams at the Web site

> certainly show (in the caulistic sense) that Drosophila is a

> progenitor (as one or more species diagnosable as Drosophila s.str.)

>  of several autophyletic genera. Okay, that is what it shows.

 

Yeah, phylogenetic trees are just that, a diagram of relatedness...

 

> My take on molecular analysis is that it shows (ignoring

> reticulation and other problems) genetic continuity and isolation of

> lineages, but not speciation events because ancestors may survive

> speciation events.

 

Duh, separation of lineages is of course not the same as speciation, and

most of the times, at least one of the ancestors will survive the event.

 

> They do, they do, as is abundantly demonstrated by the myriad

> homoplastic species, genera and families making phylogeneticists so

> uncomfortable they split and lump to hide what are commonly actually

> multiple molecular lineages of the same taxon in phenetic stasis.

 

And here we arrive at the question, what characteristics do we use to

determine whether two clades are a single taxon or multiple taxa. For

most of history, we assumed that phenotypic differences mirrored genetic

differences, but we realize more and more that this is not necessarily

the case. So, we end up with the situation that we have to decide how to

determine what are different taxa and what are not.

 

> So... If your autophyletic genera are robust in expressed traits

> important in evolution, then you have a good new classification, and

>  the model fruit fly should be renamed with a correct name in

> Sophophora.

 

Agreed.

 

> One can of course use the nomenclatural synonym "Drosophila

> melanogaster" as a kind of taxonomic DOI.

 

Yup, and this is also the easy way to deal with databases etc. Large

databases such as google already search automatically for other search

terms that are covering the same thing, for example spelling variants of

American and British, etc.

 

> What does "robust" mean? If the lineages chosen as molecular

> autophyletic genera are simply largely random sets of species, then

> one can usually find a combination of traits that by coincidence

> serve as synapomorphies for a group. This does not diagnose a robust

>  taxon.

 

Agreed.

 

> If the trait combinations (sure, polythetic is okay) are

> significantly better for the recognized genera than any other groups

>  formed by random combinations of species, then you have a robust

> genus that avoids the multiple comparisons problem in statistics.

 

What we have now is a group of species that is primarily determined by 

the history of the genus, without any sensible criteria for its 

circumscription. In fact, there is not a single synapomorphy that holds 

the genus together, primarily because of the huge variation between the 

species. Over time, various clades have been lifted out the the genus 

based on some unique morphological character, but lacking the robustness


that you talk about. At the same time, obvious clades that are really 

different and robust in many ways are left in the genus not based on 

scientific arguments, but primarily based on personal preferences, such 

as the Hawaiian drosophilids.

 

> If you want to present your research as "hard science" then you need

> to quantify the statistical analysis and do a Bonferroni

> calculation, or just a joint probability will do since this stuff is

> necessarily Bayesian as a one-time historical reconstruction.

 

Taxonomy and 'hard science', hummm.....

 

> If this seems complex, of course it is.

 

Nah.

 

> The problem with classification nowadays is the extreme simplicity

> of the evolutionary analyses on which a phylogenetic classification

> is based. Problematically, a phylogenetic classification does not

> help professional evolutionists do research in evolution because the

>  simplistic assumptions are built-in and affect the results of

> research.

 

Well, phylogenetics is a tool to do taxonomy, it is not the end all 

answer to everything.

 

Kim




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