Comments to Cladistics/Eclecticism

[Dave Walter]

Dear Thomas Pape,

Thanks for your example of a polyphyletic Department of Cryptogamic Botany
(no doubt a more interesting department to work in than one devoted to a
monophyly).  Unfortunately, your other address to a phylogeny of lichens
didn't go anywhere (changed address), but the lichen example is worth
investigation.

I minored in mycology many years ago (many mites burrow in lichens) and as
I recall the taxonomy was based on the fungal taxa (lichens are
polyphyletic, primarily Ascomycetes [from several lineages], but with some
Basidiomycetes).  The associated algae (also polyphyletic) were given short
shrift (and usually treated as unfortunate victims of fungal parasitism,
mutualism being a bit to ideologically suspect for many).  As I recall,
certain fungal-algal associations appeared to be obligate (a single
historical fate), but others appeared to be opportunistic with both (or all
three) symbiotes capable of independent existence (were early Eukaryotes
similar?).  This is a great example of exactly how messy the history of
life can be.

I don't agree with your suggestion that we adopt a Dawkinsonian approach to
evolution, although something along those lines may be the only real
solution to reticulation.  I'm sure that would make the biochemists happy,
but I have a swag of papers Taxicomers have suggested that I want to read
before I give up.

Cheers from Oz,

Dave Walter

At 10:49 AM 9/02/02 +0100, you wrote:
>Dave Walter wrote:
> > Here's a question I'm dreading some student asking me one day:
> > "If the symbiotic theory of evolution is correct, are the prokaryotic
> > domains paraphyletic and is Eukaryota polyphyletic?"
>
>The 'symbiotic theory of evolution' certainly does not make Eukaryota
>polyphyletic if we have evidence that the ancestral eukaryote symbiont and
>all her descendants are covered by that taxon name. Phenomena like
>symbiosis and hybridization will give reticulate patterns in taxon
>evolution simply because we DEFINE and NAME species the way we do.
>Eukaryotic cells, lichens, figs and fig-wasps are all examples of more or
>less intimate symbiotic relationships evolving 'together'. Figs and fig
>wasps have names of their own as there is as yet no need to name the
>combined 'lineage'. We use scientific names for lichens,
>e.g.,  http://linnaeus.nrm.se/botany/kbo/ach/ao/l1437.html.en when
>communicating about certain fungus-algal associations, yet we can still
>produce cladograms for the component lineages (e.g.,
>http://www.bot.ku.dk/staff/gargas/science.htm). Ultimately, the
>replicating DNA travelling through time still presents a dichotomous
>branching pattern.
>
>Thomas Pape - Naturhistoriska riksmuseet

Dr David Evans Walter
Senior Lecturer & Coordinator for Entomology Flexible Learning
Department of Zoology & Entomology
Project Leader, Cooperative Research Centre for Tropical Plant Protection
The University of Queensland, St. Lucia Campus,
Brisbane, Queensland 4072 Australia
Tele. (61)(7) 3365-1564; Fax (61)(7) 3365-1922
Webpage = http://www.uq.edu.au/entomology/david.evans.walter.html
Mite Image Gallery = http://www.uq.edu.au/entomology/mite/mitetxt.html
Email =  D.Walter at mailbox.uq.edu.au