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Janne, I think Shane provided a good example/explanation of what I ment, thanks, Shane

Shane wrote:in Tanganyika, 90% of the spp present all belong to the same family (Cichlidae), not nearly as impressive as the dozens of unrelated families that make up the Amazon's fishes.

Well, that is somewhat true for fish. Tanganyika actually has a large number of endemic species of other groups, notably snails, sponges and crustaceans. These groups are also very poorly studied, and diversity therefore guaranteed to be vastly underestimated (which admittedly is something Tanganyika, Baikal and the Amazon all have in common).

Malawi and especially Victoria are much younger, and there it is mainly cichlids which have radiated, with quite few other endemics.

Also as pointed out the comparison is lopsided. One would have to compare the amazon to the entire central africa, or all of southeast asia.

As for measuring diversity: remember that all there is in nature is interbreeding groups of animals. There are no genera, no families, no phyla, those are all human inventions without any necessary connection to evolution.
To avoid taxonomic issues and still be able to increase the importance of old groups with few species, there are various schemes which use phylogenies as base for some sort of diversity index. Even that isn't without its pitfalls, as it will tend to put a lot of emphasis on groups which are, bluntly put, evolutionary failures on their way to natural extinction - like, say, the coelacanths or the tuatara - while penalizing highly successful groups like cichlids and catfish. Frequently such schemes also use branch length as a factor, which means that species with short generation span or extremely aberrant species such as paedomorphic or parthenogenetic species receive inflated scores.

Pure species counts tend to strike humans as "unfair" measures of diversity (as certainly the coelacanth feels more diverse than yet another species of victoria cichlid), but personally I think it's the only measure which makes objective sense.

Bas Pels wrote:Janne, I think Shane provided a good example/explanation of what I ment, thanks, Shane

Ok, now I gotted, how many fish species are there in lake Tanganyika... ~400 species, is that correct?

Janne

Edit: lake Tanganyika, 250 species of cichlids and 150 species of other families. The water volume should be almost the same as one of the larger tributaries to the Amazon river under the rain season.

I've been reading this thread with interest..I'm not qualified to hold an opinion but my question/point is:

To what extent is man's influence a factor in the relative diversity (however one chooses to measure it) of Lake Tanganyika versus the Amazon?

For example (as I understand it) the rift lakes are important & heavily exploited fisheries, the Amazon less so?

For example (as I understand it) the rift lakes are important & heavily exploited fisheries, the Amazon less so?

The amazon is also heavily exploited of the fish industry, the different is more the size of the total covered area... lake Tanganyika have the depts still quite un explored so has the Amazon huge areas extremely poorly investigated. Tanganyika have been much more seriously investigated or more carefull than the Amazon, the chanses to find a lot more and new species is therefor much higher in the Amazon than it ever will be in lake Tanganyika.

Janne

One cannot forget the non-fishery effects that we have on both the Amazon and Tanganyika. Deforestation and damming are both major effects on the Amazon, and there are various other things such as mining and such. I know that pollution could threaten the cichlids of at least one of the rift lakes as its species use vision to recognize potential mates, and the decrease in visibility means that they're more likely to hybridize.

Ok, now I gotted, how many fish species are there in lake Tanganyika... ~400 species, is that correct?

Janne,
For the purposes of my point it really does not matter. My point was that there are many ways to count biodiversity and that a straight species count, when comparing bodies of water that are not of even remotly similar size, may not be the most accurate.
-Shane

Mike_Noren wrote:As for measuring diversity: remember that all there is in nature is interbreeding groups of animals. There are no genera, no families, no phyla, those are all human inventions without any necessary connection to evolution.

I do have a bit of a problem with 'interbreeding' - in a population of say a thousand adult individuals, producing a million fry a year, of which said thousand survive, chanses of an individual meeting a sibling will be remote - and if that happens, most likely their parents were able to produce such succesfull offspring, that it might be interesting to see what comes out, perhaps very well adapted ones.

However, for the rest I do agree fully. We need to define species, and further up, in order to be able to understand nature, but nature only has individuals and populations

Whether the population of 'Hoplos'in the Marowijne river is the same species as the one in the Surionam river or not is of no importance - untill these populations meet. Then they might end up as being 1 population, or 2

Bas Pels wrote: Whether the population of 'Hoplos'in the Marowijne river is the same species as the one in the Surionam river or not is of no importance - untill these populations meet. Then they might end up as being 1 population, or 2

I agree, there will be a mix of population and also similarity.

Shane wrote:My point was that there are many ways to count biodiversity and that a straight species count, when comparing bodies of water that are not of even remotly similar size, may not be the most accurate.

I got it again ;) The total area including the tributaries to lake Tanganyika is 231.000 km2 (the lake 32.900 km2) or just less than half of the Rio xingu valley, 50% of the area in Rio xingu valley I'm quite convinced holds more then the double amount of species than the total area incl. tributaries of lake Tanganyika; it's just so poorly investigated. I found new species everytime I go further than 20 km from the city of Belém, everytime I have been to Altamira I found many new species.

Janne

I found new species everytime I go further than 20 km from the city of Belém, everytime I have been to Altamira I found many new species.

Now you see why I am very careful when participating in "What is my catfish" postings. Hobbyists try to match up fishes in the hobby with known scientific descriptions for many reasons. The reality is that far less than half of the species out there have been described and probably as many as half of the identifications accepted in the hobby are incorrect. I am not implying we should scrap the Cat-eLog, just pointing out that hobbyists need to understand the fluidity of the situation.

The various fish numbering systems (L Numbers, C Numbers, etc) looked on the surface like a brilliant solution as they allowed hobbyists to quickly give a fish a name (i.e. L 345) without the complexity of meeting taxonomic standards nor spending days digging through old hard to find journals and books. Unfortunately this system had one great flaw. The holotype (in the sense of matching a number designator with an exact represented fish) became a photograph. This meant that the original photographer "owned" the holotype. Any book, article, etc published thereafter that did not show the exact original photo as it appeared in DATZ, for example, made the system as useless as a scientific description with no type specimen. Over time, and several publications, this has made these numbering systems completely useless. The only way they could have worked would have been for the original photo to have been deposited somewhere where all hobbyists and publishers could use it endlessly and without charge (just like a real type specimen deposited at a museum).

-Shane

Shane wrote:The only way they could have worked would have been for the original photo to have been deposited somewhere where all hobbyists and publishers could use it endlessly and without charge (just like a real type specimen deposited at a museum).

Agree completely, all publications should not use anything else than the original pictures, other pics maybe could be added as a complement but very carefully.

Janne

Janne wrote:I found new species everytime I go further than 20 km from the city of Belém, everytime I have been to Altamira I found many new species.

Janne

Thanks for the paper!

What do you think you're doing differently from these previously published studies on the Xingu? Is it a matter of localities sampled or is it possibly technique? Incompetence only works to a point; there are a number of studies on the Xingu, and the one that you sent me had seven surveys; you think after that many tries they'd have gotten something.

Incompetence only works to a point; there are a number of studies on the Xingu, and the one that you sent me had seven surveys; you think after that many tries they'd have gotten something.

They got 467 species even if many of them are identified wrong, they have missed many different types of habitats so yes, the localitys matter and the technique, each habitat requier their own method for sampling. They also covered a very small part and only in the main river and if I remember right a very small part of Rio iriri. Maybe incompetence is too strong word, should probably used "not enough knowledge" because they really try to do the best. Maybe we can change this in the future, I have just start to work together with the UFPA (University Federal do PARA) here in Belém and Braganca.

Janne

Janne, I understand that H. zebra is found in deeper waters that may be more treacherous for sampling (according to the Baensch catfish atlas). Is this true for other Hypancistrus? Also, I'm assuming that the region that they sampled called "Middle Xingu" corresponds to the region around Altamira where many Hypancistrus are found?

Hypancistrus is mainly found at deeper water like several other genus, from 5-20 meter and the best opportunity to catch them is "scuba diving" in the way they do here... which needs to be little more refined Hypancistrus can be found in more shallow water too but the main populations is in deeper water. Middle Xingu they mean around Altamira... it would be more correct to call that lower xingu because middle xingu should be around São Félix do Xingu. In the Cat-eLog for the species Hypancistrus sp "Lower Xingu" means around Belo Monte.

Janne

Janne wrote:Edit: lake Tanganyika, 250 species of cichlids and 150 species of other families

Which brings us back to species concepts. If the same species concept had been used in Tanganyika as is used for Hypancistrus, the number of species could easily be ten times that. An example: according to the Tanganyika way of looking at things, this...
http://www.cichlidlovers.com/t-m-moliro.jpg
...is the same species as this...
http://i67.photobucket.com/albums/h317/ ... iBemba.jpg
...and this...
http://www.safhl.net/davesfish/images/T ... aitika.jpg
...and half a dozen other distinct populations with distinct patterning. The situation is the same with the majority of species in the lake except for the pelagic open-water forms.

Mike,
I'm aware of the complexity both in lake Tanganyika as Malawi, we have exatly the same problem in south amerika when it comes to Loricariidae. One good example is Peckoltia sabaji... it's everywhere, another is Panaque nigrolineatus but that will soon be changed and devided into several species etc. just think on Rineloricaria lanceolata and Corydoras aeneus... how many species isn't that in the reality? I have more examples, Nannostomus eques and Nannostomus unifasciatus is all over the tropical continent of south america in almost every little stream and river... all differ slightly from each other, no one wants to use subspecies but there are a lot of localitys of enourmus amount of species except for the migrating large catfishes.

Janne

Mike, those are three distinct Tropheus species

but each has several varieties

the moliro is one specific variety of Tropheus sp "Red"
there are at least 10 different sp "Red" but those are local varieties of a single species.

the Chaitica is a variety of the true Tropheus moori species.

the Bemba is a northern variety of Tropheus sp Black.

the give-away in this case is that several species dwell together in mixed species groups. if they were the same species, they would interbreed and after a few generations a single species would be the result

at almost every part in the southern part of Tanganyika Tropheus sp Red dwells together with Tropheus moori.

same for Tropheus sp Black; it dwells together with Tropheus brichardi and on some locations even with Tropheus duboisi and Tropheus polli or T annectens

4 species of Tropheus in a single location. when you watch them as juveniles they are quite different.

still Tropheus hasn't got anything on Loricariids, cause the total number of species is about 6 or 7. some have a few varieties (duboisi has 4, polli/annectens has 3), others have many (moori, brichardi).

in Tanganyika a different color but a similar juvie, shape and size are often viewed as just varieties of a single species.

take for example the frontosa. there is 1 species or 2; but no more.
if all the different colorations, depths and sizes would be viewed through an "L number eye" or "Corydoras eye" we would end up with 40 species of Cyphotilapia......

in Malawi it's still the same as in L number land/Corydoras land or aphyosemion land. there are supposed to be at least 900 species of cichlids in Lake Malawi; wich I highly doubt. i think in their enthousiasm, the scientists made a new species out of every single variety found in the lake.......

same with south Americansd like Corydoras. an odd spot and voila: new species

in the Netherlands we used to say "every odd scale on the head of a single Aphyosemion creates a new species" , wich used to be the case back when killi fish were popular.

sidguppy wrote:Mike, those are three distinct Tropheus species

Of course they are, given any reasonable species concept which does not hinge on the fact that they are impossible to tell apart after being fixed in formalin and stored in alcohol. Which is the reason they were considered the same species.

but each has several varieties

Most of those are guaranteed to eventually be described as separate species too.

in the Netherlands we used to say "every odd scale on the head of a single Aphyosemion creates a new species" , wich used to be the case back when killi fish were popular.

And quite probably that is the, biologically speaking, correct view. If a group of animals can be diagnosed, if you reliably can tell the groups apart, then they in all probability really are a distinct species, whether they are recognized as such or not. Often the subjectivity surprises even me - killifish is a good example, when I started out with killis I remember being amazed that people actually accepted that Fundulopanchax gardneri nigerianus was the same species asFundulopanchax gardneri gardneri. Or, for that matter than the different morphs of F. gardneri nigerianus were.

Mike wrote:And quite probably that is the, biologically speaking, correct view. If a group of animals can be diagnosed, if you reliably can tell the groups apart, then they in all probability really are a distinct species, whether they are recognized as such or not.

Thats the way I would want all scientist's to work but they don't, I think it's little dangerous to interfer with nature recognizing different locality of several varietys as the same species when there are visible differencies. Why there are differencies is just because of natural on going evolution where different localities is addapted to that specific environment, even humans contribute to this development in nature moving a lot of species around the world both for good and bad reasons.

Janne

Janne,

L236 at Porto Do Moz? Isn't that close to where Xingu runs into the Amazon? I thought it was found on the other side of Altamira, in the Iriri...?

-Haakon

Many people think L236 is from Rio iriri but they are always together with L333 either from Belo Monte or from Porto do Moz, and yes Porto do Moz is at the mouth of xingu into the amazon river... strange place to find any Hypancistrus species.

I'm just waiting to find L250... have still never seen any in real.

Janne

ps. I like your signature

Really...huh. The plot thickens So, if L236 is 'always' (?) found together with L333 as you say, are they fewer and far between than L333 in the same area, or are their numbers approximately the same?

It makes me wonder if the world is being fooled here...because the untrained eye may have a hard time telling these two apart. Let's say a fisherman is collecting L333. Wouldn't there be a risk of him picking up some less striking L236 and add them to the mix, believing them to be L333? And since obviously nobody would expect L236 to be found in this area, these specimens could pass under the radar as L333 and stay that way forever? Because I don't think too many importers or buyers would necessarily be able to tell the difference...? Could this mean that L236 is actually more common in our tanks than we are aware of?

And another thing, Janne. Since you apparently know that L236 exists together with L333, you must have seen some examples of this. So, are all these L236 easy to tell apart from L333 in coloration (more striking?) or are you separating them by looking at other traits...? And is L236 still found in Rio Iriri or is this false information? I know someone wanted to try and keep the L333 location a secret too when it was first found ;)

Thanks for the signature comment, it's very true isn't it

-Haakon

The fisherman dont know the different, they are all collecting L333 that is far more common... L236 is sorted out at the exporter and of 100 L333 they or we may find 1 L236. They are very rare and easy to tell apart from L333 through their much more striking appearance, real L236 when they was allowed was always sorted out and sold to special customers, the L236 that was imported regulary to Europe or other parts of the world belongs to the Hypancistrus "Lower Xingu" complex, of course few real L236 could have been imported among other species but that was probably extremely rare consider that most exporters know the high value of this L-number.

What I'm aware of no L236 have been collected in Rio Iriri, that means that I can't be sure.

Janne

Crossbred Hypancistrus species are available in the trade, at least in Japan. Have a look here:

http://no.babelfish.yahoo.com/translate ... l=Oversett

(remember to deactivate the * in pleco to see this)


Price for this one (the most expensive): 517 U$D



Text says "Imperial zebra and cross of [niyuinperiarudatsupurudo]" and "Domestic bleeding"

-Haakon

Suckermouth wrote:

DJ-don wrote:and also how could 2 different species crossbreed in the first place?? the 2 fish must hav the same kind of dna or something (not really sure on which it is dna genes etc )

This is correct. It is possible for two species, especially closely related species, to have DNA that is similar enough to produce fertile offspring.

i have been reading through everyones post and this actually seems interesting but if 2 different species had the same DNA to make a crossbred child, wouldnt that mean at 1 point these fish MAY have been the same species???? because they have the same DNA

Hybrid parents don't necessarily have the same genes; just enough of the same to allow hybrids to be produced. Like Donkey X Horse=Mule. If the hybrid offspring are fully fertile it weakens any argument that they were legitimately separate species in the first place.
It does imply a past common ancestor provided the parents are truly different species and not just the same species with different local color forms having different L-numbers which have no scientific validity.

I expect once a thorough review accompanied by molecular genetic work has been done there will be many fewer species than there are L-numbers within the genus Hypancistrus. The fact there are local and distinctively appearing variants will not change our perspective that we should strive to breed these different variations of the same species as separate to maintain their distinctiveness in aquariums rather than indiscriminately breeding the different local varieties and ending up with a single homogenized aquarium strain.

DJ-don wrote:i have been reading through everyones post and this actually seems interesting but if 2 different species had the same DNA to make a crossbred child, wouldnt that mean at 1 point these fish MAY have been the same species???? because they have the same DNA

If, like me, you believe in evolution, then yes, all catfish species have a common ancestor somewhere way back in the past. How far in the past is part of what determines if they can cross-breed and whether the offspring is fertile.

I'd say that producing offspring that is fertile doesn't weaken the argument that they are different species - at least not with a modern definition of species. There are literally thousands of species by modern definition that are likely to produce fertile offspring, and most likely ALL Hypancistrus from Rio Xingu at least may be capable of that. To me, that doesn't make them one species.

--
Mats

MatsP wrote: I'd say that producing offspring that is fertile doesn't weaken the argument that they are different species - at least not with a modern definition of species.

I agree, Pantherophis guttatus guttatus and Lampropeltis getulus californiae are 2 obviously different snake-species but they do produce fertile offspring. Probably all species from these 2 genera are capable to produce fertile offspring with each species from the other genus (if the Lampropeltis doesn't eat the Pantherophis before mating). So if 2 animals produce fertile offspring that doesn't mean they are 1 species. It just means that they have an equal number of chromosomes and enough genes that are compatible.