Thoughts on T. pustulatus/T. lineatus hybridization

[purplecandle]

AHH, but it just needs to happen once in a while (over years) ..that could explain the small hybrid population...

BTW...does anyone know.....

are the hybrids coming from a pust populated area OR a fahaka populated area...

in other words do the fahakas end up with the pusts or is it the other way around...

if the fahakas end up with the pusts..that would make my theory more plausible...more opportunity for human intervention considering the larger fahaka population..

[maryhm]

I guess I should ask this basic question,

For those that believe in the hybrid theory, why do you believe these fish are true hybrids? Is it based solely on the fact that some adults have both lines and spots? Or is there another reason behind it?

[Corvus]

I believe (as written years ago, also try a forum search) these are either one species with regional variation or two species with the spots NOT being a inevitable character of the T. pustulatus. Even the nicest spotted ones I saw live or as pictures developed lines at some point.

I don't think the hybrid idea is very probable. Have written about that (forum search).

If there is a hybrid population, which is able to propagate, they are practically no two separate species, but one with regional variations. If hybrids were not able to propagate they would be very very few. At least much less than what is claimed to be hybrids.

[Corvus]

PS: I tried to differentiate them by their caudal like Leveque did in the past, but could not find such a large difference in caudal length or shape.

What really is needed to clear things up is: examining the original specimens (and their descriptions) with which T. pustulatus was described for the first time and compare them to T. lineatus populations at least morphologically, preferably even genetically.

[pufferpuggirl]

Thank you Corvus, you've put that to rest, at least in my mind. I really didn't believe the hybrid theory from the start, seemed too improbable to me.

[maryhm]

Thank you for your input, Corvus. I agree. Have you been able to personally view many specimens of T. pustulatus?

[Corvus]

No, only one importer here had a number to look at, which I was aware of. Of most specimens I only saw pictures. Above the most interesting are some from the Central African Museum, where the locality they were caught (Cross river near Mamfe, so to say close to the type locality of T. pustulatus) is quite well known. You can see pictures of those by Schäfer in the Aqualg book (quite easy to determine caudal length relations from these by the way). Some don't have a lot of spots.

For what it is worth, we (here on this forum) use(d) the informal term "pustuhaka" just to show that the coloration of some specimens does not indicate their classification so clearly as we would have liked. It was NOT used to indicate they might be hybrids. Sorry if this was ever misinterpreted.

PS: Please don't end the discussion, because I added my view of things. It's just my view, certainly nothing carved into stone...

[J-P]

If there was a hybrid would it be similar to a horse + a donkey = a mule?

[Corvus]

If there was a hybrid would it be similar to a horse + a donkey = a mule?

yes, that's the idea.

[emartin]

Also I don't think there has been any ichthyological study on the 'hybrid' pustulatus vs 'pure' ones and lineatus.

Until a proper study and DNA analysis is done, for all we know the 'hybrids' could actually be a legitimate variation and not a man-cause (or natural) hybridization.

And either way, as long as there are always populations of the "pure" ones that are not threatened too seriously (ie, near-endangered) it isn't that big of a cause of concern in my opinion.

For example, in Datnioides species there are what people call "oddball" datnioides most in the species D. microlepis. These look very strange (the melanin pattern) compared to what they are SUPPOSED to look like and there is fierce debate on whether they are hybrids, just a different variation, or a product from suspected hormone injection breeding.

So my point is, although it is likely they are hybrids (the "pustulakas"), we still have to leave open the possibility that it could be a legitimate variation in the species.

Take into consideration Labidochromis caeruleus. Found lake-wide in Lake Malawi, it has dramatic color variant and melanin variation from being blue, ice-blue/white, white, solid white with no black on the dorsal fin (Ruarwe is that location I think), and then yellow and half yellow half white.

Or Tyrannochromis nigriventer. That species has EXTREME melanin pattern variation to the point that for decades (and still today) people erroneously think that T. nigriventer Southern is actually T. macrostoma! (almsot all captive raised T. macrostoma are mis-identified and actually are T. nigriventer Southern).

The northern varieties of T. nigriventer are the common ones you see in the hobby captive raised, they have strong vertical or broken barring, while the southern variety is more elongated and has solid (1-2) horizontal lines similar to the ones found on REAL T. macrostoma hence the mix up. I'll get photos up soon comparing them so you can see what I referring to.

So at the moment I am on the same boat as 'pustulakas' being hybrids but I still believe we should be clear they could be a legitimate population variant at a specific location.

[emartin]

What really is needed to clear things up is: examining the original specimens (and their descriptions) with which T. pustulatus was described for the first time and compare them to T. lineatus populations at least morphologically, preferably even genetically.

Exactly! That is what Ad Konings is doing in Lake Malawi as there used to be tons of synonymous species in the lake (there still are in my opinion).

The fish need to be compared with the original taxonomic description as well as biologically compared with "pure" pustulatus and pure lineatus to make a conclusive determination that they are hybrids or possibly a legitimate population variant.

[Hierony]

I personally agree with the flow of opinion that the geographical separation of the two species would prevent hybridization, however I think it is important to note there are certain crosses between different species which will produce fertile offspring. The most common I was able to find is the offspring of a Grizzly Bear and a Polar Bear. The most important characteristic of these hybrids is they are naturally occurring. While terrestrial creatures (within limits) have an easier time crossing over into uncommon locations, the Polar Bear and Grizzly occupy extremely different niches. Polar Bears primarily hunting on ice drifts and regularly swimming, seem an unlikely match to encounter Grizzly Bears in any situation which reproduction would be an option, but it is being documented there are wild hybrids in existence. With this in mind it is plausible there could exist a cross-breeding population creating a new variant of T. lineatus and T. pustulatus. As has been stated before without a full genetic sequencing of a large sample of both species and possible hybrids it is very difficult to know for sure. After all, the animal kingdom has this wonderful ability to be completely oblivious to the categorical system we humans use.

[Corvus]

Yes, there are fertile crosses. But if the species-concept is taken strictly this means the original two species are in fact one biological species with two subspecies. This is well known by scientists, but is not easy to change and communicate to the public. Polar bears are practically a subspecies of U. arctos, just as the Grizzly is such a subspecies. You'll find this view of the polar bear in every newer genetic or systematic study. The reason for their genetic similarity is quite easy: the polar bear is a very young species, probably only about 150.000 years old and still compatible. If they live on for another 100.000 years, they likely won't be compatible anymore and can be considered a separate species. Such processes are basically the origin of species.

Natural hybrids - even if they occur - are a quite rare compared to individuum numbers of the oringinal species. In contrast, the number of those unclear puffers compared to the number of clearly identified T. pustulatus is quite high. This makes the hydrid idea with regard to these puffers very questionable and improbable.

[Hilly]

Been trawling through old posts on other forums, found one on AP of 2 juvenile Pustulatus. The first one at 5" without a second glance could be said to be a Lineatus if it wasnt for the extra spots, then the one underneath looks more like a small Pustulatus. I then read somewhere else about specimens that have the combo of lines and spots that have popped up being sold as Pustulatus that the importer was dubious about.

So could it be a possibility that it isnt as clear cut as just Pustulatus or Lineatus, perhaps another unclassified sub-species that hasnt been properly documented.

This is probably ground that we have covered before but always good to refresh.

Juvenile Pustulatus

Either way it seems that the specimen in the pedia just isnt the norm and is an exceptional one.

This seems more the norm for younger ones
Image pic halfway down the thread.

But then I saw this one in someones photobucket account and its a beauty and a big one.

[maryhm]

The identification key link I posted earlier in this thread says that juvenile Lineatus exhibit red spots. So I'm not surprised that the juvenile "Pustulatus" that were purchased turned into Lineatus. The more I delve in to this, the more I'm convinced that getting a true pustulatus will be no easy feat! Honestly, I think you'd have to get one at around 6" to be sure.