> >These two are the same species, they only differ at the subspecies
> >level. It is a somewhat arbitrary split, there is at least one inornata
> >around Weipa that looks just like a rubrostriata.
>
> I couldn't stand longer. Sorry, Peter. This isn't obvious for every
> scientist. According to some more recent publication of Mayr (the
> grandfather of the modern species concept, I think he still lives
> but must be about 90 years old now) a subspecies necessarily
> requires a hybridization zone.
No it doesn't. (Mayr is still living). From Animal Species and
Evolution, Ernst Mayr, 1963.
"A subspecies is an aggregate of local populations of a species,
inhabiting a geographic subdivision of the range of a species, and
differing taxanomically from other populations of the species."
I think you may be thinking of something a little different along the
following lines, subspecies cannot occur sympatrically (in the same
place versus allopatrically, meaning not in the same place), or else they
would intergrade with one another (hybridise is not the correct terms as
only species can hybridise). If they did not interbreed in sympatry then
they would have to be considered different species. This is the
definition I was brought up on and still current today according to our
local population geneticist on campus.
> To my opinion 15,000 years may be long enough to evolve the tri varieties.
What characters are you considering here though? They vary relatively
consistently in colour and body depth. However, body depth, as I pointed
out may be strongly determined by environmental factors, and thus not a
very good characteristic to judge the fishes differentiation by. Despite
your misgivings relative to genetic studies they would be useful in this
area. Assuming we can agree that tris on the eastern side of Cape York
and north of Daintree have had a longer seperation relative to those in
the rivers that would have drained into Lake Carpentaria. Thus,
genetically the populations around the Gulf should be more closely
related to one another and far more uniform than those on the eastern
side. Similar work was done on barramundi and that's exactly what they
found and the reason they hypothesised for it.
Tootles
Peter Unmack