My Mail program adds the previous message..just deal with it :-)
Roy Hunter
ANGFA NA
http://ourworld.compuserve.com/homepages/royhunter
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> From: peter.unmack at ASU.Edu
> To: rainbowfish at pcug.org.au
> Subject: Re: [RML] RE: Re: M. herbertaxelrodi/trifasciata
> Date: Sunday, December 15, 1996 4:22 PM
>
> On Sun, 15 Dec 1996, Roy Hunter wrote:
>
> Next time Rooster why don't you try and not include the original message
> in your response 'cause now I have to delete it all and I can't just
> highlight it all and delete like someone in windoz.
>
> > I cant recall the name of the "line" separating species from Sahul to
the
> > surrounding islands.
>
> There are two or three, but the one you are most likely referring to is
> Weber's Line. Another less well accepted line is Wallace's Line.
>
> > Would you think that rainbowfish have evolved since
> > Sahul collided with the other plate in that area?
>
> You are overlooking the fact that Weber's Line is a barrier to freshwater
> fish only. If rainbowfish had evolved from a marine ancestor in the last
> 15 million years or so (when the Australian plate started to collide with
> the Asian one) then that marine ancestor would have been able to cross
> Weber's Line and you may expect them on both sides of the line.
>
> > Or did the rainbowfish of Sahul begin evolution before the
> > collision of Sahul with the surrounding land masses therefore Bedotia
and
> > Telmatherina would not be related.
>
> Well, they are still related, just not sister groups. They all share a
> common ancestor but there has been significant divergence within the
> various lineages.
>
> OK, lets try this out. This is purely hypothetical. 80-100 mya most of
> the souther continents are joined or relatively close to one another. An
> ancestral bow occurs in estuarine areas. At some point in time, perhaps
> due to continents drifting and changes in marine currents this species
> gets split geographically. One gets stuck off Africa and for whatever
> reason it adapts to and invades freshwater on Madagascar and undoubtably
> elsewhere in that region a long time ago. Thus, you have the bedotia
> lineage. The other does the same in Australian waters. This fish
> spreads across Australia gradually and colonises New Guinea and perhaps
> some of the islands to the West of it. These things then diverge into
> rainbows, blue eyes, and telmatheriniids over
> long time periods and eventually all mix back into together again. By
> this time, they have all significantly diverged along different paths and
> have formed distinct lineages such as rainbows, blue eyes, and
> telmatherinids. Through various later range expansions and isolations
> you get the various genera we see today forming. One thing too worth
> pointing out is that I am not sure how well it is accepted that
> telmatheriniids and psuedomugils are sister groups. I think there is
> some disagreement here.
>
> > If they are related then what are the
> > common traits shared between them and the Sahul rainbows??
>
> >From Dyer and Chernoff. All Melanotaeniidae have 6 features: posterior
> myodome restricted to the prootics, absence of second dorsal fin spine,
> three or more pleural ribs posterior to first anal pterygiophore, greater
> body depth, reduction or loss of the silvery lateral band, sexual
> dimorphism in body colour and median-fin ray elongation.
>
> Probably not quite what you were expecting huh? :-)
>
> > wouldn't you be
> > able to then isolate the marine fish that is responsible for this than
just
> > to say possibly "silversides"??
>
> That assumes that their ancestor is still around today unchanged from
> when rainbows split from them. Many species change slowly over time
> without any isolation, this is one aspect of classic Darwinian
> evolution, slow and gradual change. This means there are no branches in
> the family tree. For instance, if you look at recent human evolution,
the
> species that existed before Homo sapiens is no longer around today. This
> is because it and us are just two different points on the same line. It
> changed and became us. Thus, it never really went extinct. This is
> kinda difficult to explain. Hope you can understand. My point in all
> this is that whatever was around when rainbows first evolved would most
> likely be somewhat different today also. Fish morphology changes with
time.
>
> Tootles
>
> Peter Unmack