Roy Hunter
ANGFA NA
http://ourworld.compuserve.com/homepages/royhunter
----------
> From: peter.unmack at ASU.Edu
> To: rainbowfish at pcug.org.au
> Subject: Re: [RML] RE: Re: M. herbertaxelrodi/trifasciata
> Date: Saturday, December 14, 1996 10:25 PM
>
> On Wed, 4 Dec 1996, Harro Hieronimus wrote:
> > Peter Unmack wrote:
> > >On Fri, 29 Nov 1996, Harro Hieronimus wrote:
>
> I've left in what text I figured was neccessary for folks to understand
> the arguments going on. This'll kill most a ya. :-) Read on only if
> you dare. Warning: this message could be dangerous to your health. Go
> find someone else to complain to when you go cross eyed trying to read
> it! Much of the arguments contained within are all subject to question
> and no one has the right answer. We can only sit around and bullsh!t
> about it and make ourselves feel important and like we have conquered
> something bigger than us all. :-) Mind you, the human imagination is
> probably bigger, especially in some folks. Enough dribble, onto
> rainbowfish evolution!!
>
> > >> Well, there are several arguments why rainbowfish are a rather young
> > >> family.
> > >> 1. There relatives are also rather modern fish.
> >
> > >What do you consider their closest relatives to be? I know there has
> > >been some recent work done on the relatedness of the various families
we
> > >are interested in. However, I have not seen any of it. If anyone has
> > >any references to it I would be greatful.
> >
> > I'm not quite sure what their real closest relatives are but we have
> > to look for them in the Telmatherinidae and their relatives.
>
> More for info than anything else. This paper reverses some of the
> classification thinking of the past. Past work has tended to look from
> the bottom up, ie from species to genera to subfamily to family etc.
> This study more looked from the top down, ie series, order, suborder,
> infraorder, superfamily, family, subfamily and tribe.
>
> Dyer & Chernoff. 1996. Phylogenetic relationships among atheriniform
> fishes. Zoological Journal of the Linnean Society. 117:1-69.
>
> This is in no particular order. This will probably get all screwed up on
> some folks email programs, sorry.
>
> Melanotaeniidae|-Melanotaeniinae--------------------------|-Melanotaenia
> (Family) | (subfamily) |-Glossolepis
> | |-etc etc
> |
> |-Pseudomugilinae-|-Pseudomugilini (Tribe)-|-Pseudomugil
> | | |-Kiunga
> | |
|-Scaturiginichthys
> | |
> | |-Telmatherinini
(Tribe)-|-Kalyptatherina
> | |-Paratherina
> | |-Telmatherina
> | |-Tominanga
> |
> |-Bedotiinae-------------------------------|-Bedotia
> |-Rheocles
>
> No doubt this will change later as these things always seem to. I know
> Dr Ivantsoff's lab will be in disagreeance with it. :-) A
> couple of quotes from the text. "Relationships among the melanotaeniids
> are only tentative, but they do indicate that pseudomugilins and
> telmatherins are sister groups. The relevance of this phylogenetic
> hypothesis to the biogeographic history of the Indo-West Pacific region
> is significant because Melanotaeniidae is a monophyletic group of
> primarily freshwater fishes."
>
> Also from the paper, Melanotaeniinae share a common ancestor with
> Pseudomugilinae which branched off after the Bedotiinae did. Thus, the
> closest relatives to Melanotaeniinae are the Pseudomugilinae according to
> this paper. One thing Dr Ivantsoff mentioned to me is that his PhD
> student, Aarn Whitehouse feels that Bedotiadae and Melanotaenidae (using
> older classification) split around the Eocene (~50 mya) when Oz, India,
> and Africa split off and I guess hadn't drifted too far away.
>
> > >> 2. These fishes are still closely related to other fish which have
the
> > >> same history, coming from seawater relatives and invading fresh
water,
> > >> like Telmatherina and Bedotia.
> >
> > >Do we really know that fish such as Bedotia and Melanotaenids
originated
> > >from salt water? Based upon what evidence? Allen suggests
melanotaenids
> > >are freshwater evolved since they have not crossed Webers Line. If
they
> > >were marine they could have swum it as it is not that far apparently.
> >
> > Yes, we know. Australia - together with New Guinea - has left the
ancient
> > continent (forgot the name, the stage before Gondwana) very early.
Thus
> > if it were primary freshwater fish they must be very very old - like
lungfishes
> > and species like Scleropages. Sign of old species is, that they don't
evolve
> > strongly (as the two Australian species didn't do).
>
> Australia and Antartica were last to break away, everyone else had split
> before that. Guess they just didn't like their neighbour much? :-)
>
> Actually, up until fairly recently, the last million or less years there
> were quite a number of lungfish species which are now extinct (around 9).
> You cannot say that _only_ old species don't evolve strongly, sure, that
> may be the case in some but not in all.
>
> > Rainbowfish still seem
> > to be in the course of evolution. According to all what we know in the
> > evolutionary biology that's a sign of a rather young (that's relative,
also
> > a few million years is young) family.
>
> I can't say I've heard of this before. Do you have a reference for that
> statement? I also can't say I agree with it either. This is also fairly
> subjective and thus not going to be resolved by us either. :-)
>
> Based upon what evidence are they thought to be young? They show
> tremendous variation in colouration. Other than that they are relatively
> similar morphologically. They all share the same basic body plan.
> Craterocephalus, Ambassis are all just as hard to distinuish
> morphologically. If you look at the key to rainbowfishes it's amazing
> how important colour is in distinuishing them. Now, I'm not doubting
> present rainbowfish taxonomy, but if they were a plain grey fish (largely
> like Craterocephalus and Ambassis are) would we have the same taxonomy
> today? Would we still think they are young species? Take a look at a
> key to Ambassis or Craterocephalus, no colour, and it's damn hard to tell
> many of them apart. All I am trying to point out here is that we have a
> highly variable trait (a single characteristic--colour) that we seem to
> regularly give considerable weight to while forgetting the rest of the
> fishes characteristics.
>
> As far as using evolutionary theory goes, I think this is a little
> dangerous or potentially misleading. On it's own it is pretty weak.
> Combine that with geological evidence and I think you have a very strong
> case. To me, the geological evidence suggests a very old lineage of
> fish. There are still many questions left unanswered regarding the
> geological record too, but I think it has more credence than evolutionary
> theory.
>
> > >> 4. Strong speciation in M. trifasciata and M. splendida and others,
> > >> which is a sign for modern fishes.
> >
> > >Why? Pupfish (Cyprinodon) as a genus have been around well in excess
of
> > >10 million years, probably more like 30 and they are very speciose.
> >
> > Are they? Or have they been? Most pupfish are at the end of their way.
If you
> > have such an extreme isolation under extreme conditions like in pupfish
> > you will find speciation of extinction. I don't think they are much
older than
> > 10 million years - and thus a rather young family.
>
> Pupfish are presently more widely spread than rainbowfishes are. I'd
> hardly call them on the way out. They will be around for a few years to
> come since they tend to specialise in habitats that other fish cannot
> survive in. As long as these habitats remain so will pupfish. Not all
> pupfish have severe isolation either. C. variegatus occurs from the
> north eastern US all the way through the Gulf of Mexico.
>
> > >> Rainbowfish are thaught to have an age of a few million years,
> > >> maybe two or three.
> >
> > >Define rainbowfish. Do you mean Melanotaenidae, Melanotaenia, or
> > >something else? According to paleontologists the average age of a
> > >species in the fossil record is 6 million years. Who thinks they are
2-3
> > >million years old? What is your source of this information?
> >
> > E.g. look into Jerry's new book.
>
> You still didn't define what level of taxonomy you consider to be 2-3
> million years old. :-) This is an important distinction to make.
>
> I took a look at Jerry's books. A few quotes from them;
>
> "There are no known fossils of rainbowfishes, although insufficient work
> has been carried out on more recent fossil strata of the Aust-NG region."
>
> "Eventually it (the ancestor) evolved a purely freshwater life cycle,
thus
> setting the stage for the explosive speciation of rainbowfishes in
> relatively recent times, perhaps within the past 200,000 years."
>
> "There appears to be little doubt that the group originated in fresh
> waters of the Australian continent as there are no closely related forms
> occurring outside of this region. Although some species of Pseudomugil
> are found in salt water or brackish estuaries, as previously mentioned,
> the family as a whole has had little success in crossing marine barriers,
> even if very narrow."
>
> Note that there is very little geology mentioned.
>
> As an alternative;
>
> Crowley. 1990. Biogeography of the endemic freshwater fish
> Craterocephalus. Memoirs of the Qld Museum. 28(1): 89-98.
>
> She proposes that there were two invasions into Australian freshwaters,
> the first was the "eyresii" group around 110-95 million years ago, the
> second was the "stercusmuscarum" group around 35-25 mya.
>
> "Although Whitley (1959) and later authors (e.g. Allen & Cross 1982;
> Merrick & Schmida 1984) considered the freshwater fishes of Australia to
> be of recent origin, I suggest that despite the present lack of atherinid
> fossils in Australia ... hardyheads at least (and most probably
> rainbowfishes with similar species distributions) are not the result of
> recent speciation." She bases this statement on the geological history
> of Australia and the potential routes for dispersal across the
> continent. It is very difficult to get a species such as splendida from
> on end of Oz to the other in 3 million years.
>
> For instance, consider fluviatilis and duboulayi. The former is inland,
> the latter is coastal. There are many species pairs which occur on both
> sides of the dividing range. Southern and Oxylean pygmy perch, mountain
> galaxias, two species of Murray cod, Murrray and Marjorie's hardyheads,
> two carp gudgeons and others. It is also worth noting that several
> species come down the east coast as far as the Clarence River (or around
> about) and then jump into the Murray system. There are known river
> captures in the headwaters of the Clarence when the area was last
> volcanic 20-23mya. No doubt river captures continued to occur as
> rivers cut through various lava flows. Irrespective, there don't appear
> to have been any recent captures indicating that the opportunity for
> dispersal have been limited for a long time, seemingly more than a couple
> of million years. That area appears to have been an important dispersal
> route based upon todays distribution patterns. Unfortunately, we don't
> know how well this reflects past distributions and we will never know for
> sure. That's were genetic data can really assist in biogeographic
> interpretations. Now, even I have trouble accepting these dates as it
> just seems too old. However, you have to go with the best supporting
> evidence of the day and try to further refine and test that hypothesis
> and improve on it/change it etc.
>
> Further to this, the apparent closer relationship between Bedotiinae and
> other Melanotaeniidae to me suggests old age. Madagaskar has been
> isolated for a long time from everything (I don't know how long, anyone
> know?). If there was a recent ancestor it would have to have been very
> widespread across the Indian Ocean. Why would it's distrition be so
> disjunct today? Obviously there are many possibilities here, none of
> which are testable. It's just that the two places are a long way apart.
> Also, if it were a recent marine ancestor why does it only occur (or at
> least primarily) on the Australian side of Weber's Line? Especially
> since that line has existed for several millions years or more.
>
> Also, if it were a recent marine ancestor why can't all but a couple of
> species (blue eyes) of the Melanotaenidae (as defined by Dyer and
Chernoff)
> tolerate more than 50% salinity levels? Now, many folks have suggested
> that the higher than normal salinity tolerance of Australian fish in
> general is indicative of a recent marine origin, however, this overlooks
> that fact that over Australia's history salinity has been somewhat of an
> evolutionary force that fish have had to adapt to, if they couldn't they
> went extinct. Few continents have "fresh" water that gets as saline as
> regularly as parts of Australia.
>
> > >Only if the genus Melanotaenia is monophyletic. This just means they
all
> > >came from one ancestor, vs polyphyletic, meaning that there is more
than
> > >one ancestor to the genus. There is some evidence that the genus is
not
> > >monophyletic as we presently recognise it. The work of folks at Qld
Uni
> > >found that M. affinis was as distinctive as G. incisus from the
> > >Melanotaenia spp they examined. This suggests there is something
wierd
> > >going on (and also that M. affinis aren't very closely related to
> > >goldies, herbies, or tris as Allen first proposed).
> >
> > I still believe Melanotaeniidae are monophyletic. What work?
> > And most of all, what method? Do you remember my critics
> > on some of the "modern" methods which create results they want to have?
>
> Zhu, Jamieson, Hugall, & Moritz. 1994. Sequence evolution and
> phylogenetic signal in control-region and cytochrome b sequences of
> rainbow fishes. Molecular Biology and Evolution. 11(4): 672-683.
>
> You can critise genetics all you want, the fact remains that the genetic
> code doesn't lie, only the interpretation can. While their results may
> be considered somewhat tentatively (since it is a first up effort and
> not every species was examined) that was one of their most conclusive
> results.
>
> > >> The history tells us that M. trifasciata and M. herbertaxelrodi have
been
> > >> isolated for a very long time. While M. trifasciata developed a
great lot
> > >> of varieties M. herbertaxelrodi did not - because there may have
been no
> > >> isolation in the Lake Tebera area..
> >
> > >That was certainly not one of my arguements. You wouldn't expect to
see
> > >differentiation when you only have one population, ie Lake Tebra.
> >
> > Wrong, see Lake Malawi and Lake Tanganjica and, as far as we know
today,
> > M. boesemani and M. ajamaruensis as well as C. fasciata and C.
sentaniensis.
>
> You can't compare cichlid evolution to rainbow evolution. Cichlids are
> very outstanding and unusual when compared to most other fishes. Sure,
> you give two examples where I am incorrect, but how many examples are
> there where this is not the case? I would suggest that your two examples
> are out of the ordinary. Mind you, this is kinda off topic and a mute
> point anyway (as is most of this since no one can actually PROVE
> anything!). :-)
>
> > >> In a family were species tend do develop varieties very quickly (and
the
> > >> tri's varieties had only about 10.000 years)
> >
> > >Sure, rainbows tend to develop _colour_ varieties "relatively"
quickly.
> > >So what? Why did the tris have only about 10 000 years to do this?
This
> > >may be true to a degree _if_ they occupied the lake that once existed
in
> > >the Gulf of Carpentaria. However, I don't think that is the reason
you
> > >are suggesting. You are presumably saying they only invaded
Australian
> > >waters 10 000 years ago? Why couldn't they have done it earlier
though?
> >
> > I'm quite sure that a common ancestor of all tri's we know lived in the
waters
> > which are now partially filled with the Gulf of Carpentaria. I don't
know if
> > there already were varieties (I haven't been there, see above) but
there was
> > even theoretically a gene flow between all of the varieties living
today in
> > rivers ending in the Gulf. The M. trifasciata ancestor has surely been
older,
> > but I think that the varieties are really young, about after last ice
age.
> > One sign (no proof) is that you can't find two rivers which aren't
connected
> > having the same variety.
>
> The varieties that live on the eastern side of Cape York and probably
> some around Darwin didn't have recent contact with the lake in the Gulf
> of Carpentaria. There aren't any known recent connections between these
> areas, especially eastern Cape York. Bruce, wanna comment on Harro's
> last comment re two rivers which aren't connected having the same (or at
> least very similar) colour varieties? Aren't some of the fish around
> Nhullumby similar to one another?
>
> > >> Tri's are rather deepbodied at least when they become old. Herb's
are
> > >> never as deepbodied. And this is (!) astonishing as a lake dwelling
species
> > >> which would just be a variety of a stream dwelling should be much
more
> > >> deepbodied!
> >
> > >Perhaps tris were once a lake adapted fish, thus the reason for their
> > >deep, rather than slender bodies. It's interesting to note that those
on
> > >the eastern side of Cape York tend to be more slender. It gets more
> > >interesting when you consider that around 10000 years ago there was a
> > >massive freshwater lake in the Gulf of Carpentaria (three times bigger
> > >than Lake Bonneville which once covered ~1/5 to 1/4 of Utah!) to which
> > >many of the rivers presently containing tris would have drained into.
> >
> > 10.000 years are long enough to loose a deep body. However, it's still
> > a hypothesis.
>
> How many tris actually live in an environment with strong enough flow to
> select for a less deep body? Many of them tend to be pretty slow in the
> dry season aren't they? Several bows, such as M. oktediensis and M.
> monticola can both be relatively deep bodied yet live in quite high
> gradient streams. Again, kind of a moot point that drifts off the track.
>
> > >Further food for thought on rainbowfish ages. M. exquisita primarily
> > >(only??) exist above waterfalls in the Katherine and Alligator Rivers
> > >(and maybe elsewhere in that vicinity). How old are these waterfalls?
I
> > >would argue that exquisita were present before the waterfalls. At a
> > >later point, a splendida invaded the area and exquisita disappeared
either
> > >through competition or hybridization below these waterfalls. It is
> > >notable that the Qld Uni folks found that M.s. australis from the NT
had
> > >mtDNA's very similar to exquisita which they felt was was likely to
> > >introgression (hybridisation) between them. And some folks firmly
> > >believe rainbows don't hybridise in the wild. :-) Although, you
should
> > >note, this probably happened a long time ago.
> >
> > You're surely right with your idea on the distribution of the species.
> > However, we also find this in other fish and I'm quite sure the
waterfalls
> > aren't very old. The are in the tropics, were landscape changes very
quickly.
> > However, we have to know more about the geology to be sure.
>
> Hey Bruce (or anyone else) if ya happen to talk to Dave Wilson see if he
> knows anyone that may know some age of those waterfalls above which
> exquisita occur. I might try and blip Helen Larson and see if she knows.
>
> > I think that the RML should not only consist of SPAM ;-) but also
> > some more sophisticated items :->> Let's work for a good mix.
>
> Life on the RML without spam is just not immaginable. :-) Spam is
> good! spam spam spam spam spam spam spam spam spam spam.......
>
> You get the picture..... :-)
>
> Tootles
>
> Peter Unmack
>
>