Morelia spilota Complex/ Intergrades

[zen]

Inspired by the discussion generated by the striped Intergrade recently advertised on Herptrader, I thought an examination of the Morelia spilota complex was due.

There seems to be some confusion as to what constitutes a hybrid and exactly what an intergrade is.

I'll start with a great wrap by Dicco as an intro.

A hybrid is a cross of two things, if you cross a Morelia bredli with a Morelia spilota it is a hybrid, if you cross a Morelia spilota spilota with a Morelia spilota mcdowelli it is still a hybrid. The fact it is a sub-species dose not effect whether or not it is a hybrid, it is not a Hybrid between two species, but it is still a Hybrid, just at a sub-species level.

The word intergrade is refers to something that has either gradually changed from one thing to another or where two things gradually come together.

A hybrid between two Pythons, whether it is a full species or sub-species hybrid, is not something that has happened gradually.

Even if two species or sub-species cross in the wild they are Hybrids, it dosen't matter how they are created, a Hybrid is a cross between two things, whether naturally or with the assistance of humans.

The Natural Intergarde Pythons found on the Northern Coast of NSW are not just where a Carpet Python, Morelia spilota mcdowelli and a Diamond Python, Morelia spilota spilota have met and hybridised, in fact their ranges are separated by the Natural Intergrade Pythons, which are called Port Mac Pythons sometimes to save the confusion.

The Intergrades on the North Coast are a seperate varient of Morelia spilota, as are all of the different varients of the species that gradually changed and adapted to it's environment like all other reptiles in Australia.

Most of the animals in Captivity are Hybrids being sold as Intergrades, and there are very few True Intergrade Pythons in Captivity. The true Port Mac(Intergarde) Pythons don't just look like a Diamond/Carpet Cross, they have their own unique traits as do all of our M. spilota forms.

I agree with everything Dicco wrote here but would like to add that true intergrades are not just restricted to Port Macquarie of course. They're found over a fairly wide area of that part of the mid-north coast of NSW.
As long as people don't take names like this too literally.
Terms like this seem to work O.K for the Carpets in Queensland, like Proserpine, Atherton, Tully etc. Though it must be understood that these locality names are regional rather than specific.

I've heard that it's quite complex in the mid-north coast with apparently pure Diamonds and pure Carpets found in the same area along with intergrades. It seems that they seek out others of their kind to mate with retaining subspecies integrity.
It's been suggested that intergrades are a valid subspecies!

 

[Sdaji]

Look up 'intergrade' in a biological dictionary, you'll generally not find an entry. I found an older (1992) biological dictionary in an op shop today, which had an entry, but put it as synonymous with hybrid.

What Dicco said about hybrids is true, it doesn't matter whether it's natural or not and as you'll find if you actually look up the definition of hybrid, a hybrid is just the offspring of two non identical individuals.

Why is it that when people say "intergrade" they immediately think of intermediates between Sydney Carpets and Brisbane Carpets? Carpet Pythons vary all along the east coast. A typical Carpet Python from the southern extreme of their range doesn't look the same as a typical one from Sydney, which doesn't look the same as a typical one from Gosford, which doesn't look the same as a typical one from Port Macquarie, which doesn't look the same as one from Brisbane, which doesn't look the same as one from Proserpine...... if what keeps getting called an intergrade is an intergrade, then any Carpet Python on the east coast is an intergrade (between whatever is to either side, or the surrounding area). The same can be said of almost all Children's Pythons (broad sense), along with most species. If the largest city in the country happened to have been built where Pt Macquarie is, there would be a name for that type of Carpet Python, if the next largest city happened to be somewhere far north of where Brisbane is, perhaps Brisbane carpets would recieve the stupid intergrade label.

 

[zen]

Sdaji, so basically you're saying that the term "intergrade" is a misnomer, it seems.
Populations blending gradually, with fuzzy boundaries, rather than retaining subspecies integrity.

I notice that you refer to Sydney Diamonds as Sydney Carpets. Is this because you don't believe that the Diamond is a valid subspecies?. :?

Morelia bredli differs from Morelia spilotain that it has more than 9 scales across the top of the head between the eyes. It's therefore considered as a seperate species.

The Morelia spilota subspecies however are considered morphologically identical, except perhaps the boof head and generally larger maximum size of mcdowelli. The Jungles similarly are different in size, being generally smaller than any other Morelia spilota.
Lord Cogger only seperates the Morelia spilota subspecies according to range.
e.g. M. s. imbricata - southern WA

Colouration it seems is not a valid distinguishing characteristic.

So I agree that if range is what seperates the subspecies, then the more or less continuous and overlapping ranges of the remainder of Morelia spilota subspecies would therefore blur the subspecies.

 

[jordo]

I agree with Sdaji, there will never be a clear line to distinguish between localities and also we can't really use terms like a "typical carpet python" without raising the question, whats typical?

 

[geckodan]

I have generally avoided this topic but I just can't hold out any longer.
My appreciation of the difference between hybrids and integrades comes from examples in both reptiles and birds.
IMO " intergrade" is a term that should be restricted to use for naturally occurring hybrid populations that have over many generations IN THE WILD developed into their own unique population. This requires that two very similar species (the fact that they are able to hybridise and produce fertile offspring does go against the true definition of a species and therefore suggests that subspecies nomenclature should be investigated) or subspecies are geographically adjacent each other and this results in hybridisation at the range boundaries. Over time, this natural hybrid boundary becomes its own barrier. This occurs with our well known carpet python debate but also occurs with species such as spinifex pigeons (natural hybrids between red and white bellied forms) . In captivity, if we are offerred offspring that are the articial result of pairing a white bellied spinifex with a red bellied spinifex it is a HYBRID. If we are offered individuals that originate from the area of overlap then they are considered INTERGRADES and are able to validly recieve the subspecies staus designated for that population.
The carpet python/diamond python thing is no difference. For me, an artificially produced offspring of a carpet and diamond is a carpet/diamond hybrid. An individual snake which has its original parentage based on the animals which naturally occur in the overlap INTERGRADE zone is the only animal which can carry this tag.

In summary, IF WE MADE IT, IT IS A HYBRID.,
IF NATURE MADE IT AND IT HAS EVOLVED IN THIS WAY IT CAN EARN THE NAME INTERGRADE.

 

[Sdaji]

No zen, but every other type of carpet python gets called a carpet python. The term "Diamond Python" is obsolete, it is a term created when it was supposed that there were diamond pythons (M.s.spilotes) and carpet pythons (M.s.variegata) which all other Morelia spilota were included in. We now recognise that there are many different types of carpet pythons, not just two.

Some of the snakes which were originally thought to be in the "carpet python" category (before it was recognised that there was any reason to call the different "carpet pythons" different subspecies) are considered to be more different from the type specimens of carpet pythons than from diamond carpets ("Diamond Pythons"). Most people now think that snakes such as South Western Carpet Pythons are more different from Brisbane Carpet Pythons than Diamond Carpets are from Brisbane Carpets, so if a Diamond Carpet isn't a Carpet Python, neither should be the South Western Carpet, or many other Carpet Pythons. We call all the other Morelia spilota subspecies carpet pythons, recognising that they're all from the same species.

So far I have never seen anyone else take this view (I've never really discussed it with anyone, but I've never heard anyone call a Diamond Carpet a carpet python) and I stand alone on the issue (not the first time it's happened!) but I'm also yet to have anyone disagree with me.

Jordo: I'm not suggesting that different localities don't have very distinguishable phenotypes. They certainly do. There is a lot of variation between and within localities and it's extremely difficult to deal with taxonomically, because where you draw lines between taxa is often arbitrary. There is more or less continuous gene flow right along the east coast. It's like shades of grey in some cases, but in others it's even more complex.

 

[olivehydra]

If people who define an integrade as something that occurs "over time" and is multi-generational, then does the offspring of a pairing between an integrade and a non integrade have a reduced rite to the term "integrade", as opposed to a pairing between two "pure" integrades?

 

[Sdaji]

geckodan: I think the problem with carpet pythons is that people don't realise that the carpet pythons intermediate between what you get in Sydney and what you get in Brisbane are not hybrids, they haven't come into existance from a Brisbane type carpet breeding with a Sydney type carpet. Not at all long ago (only about five years) it was widely believed that there were "Carpet Pythons" and "Diamond Pythons" which lived virtually side by side, and these occasionally met up and hybridised, the offspring then generally fading away and never giving rise to long lasting populations. This view, or a watered down version of it is still fairly commonly held. It's a bit like saying that Proserpine Carpets don't form a real population, it's just that occasionally a Brisbane Carpet Python Crosses with a Townsville Carpet Python. We can all see that is stupid, but for some reason this is the way Brisbane, Sydney and their intermediate carpet pythons are viewed.

Perhaps it would help some people to think of it along the lines of it being impossible to create a Proserpine Carpet by crossing a Brisbane and a Townsville Carpet. (Or a Brisbane with a Darwin to produce a cape york!)

 

[geckodan]

Most people now think that snakes such as South Western Carpet Pythons are more different from Brisbane Carpet Pythons than Diamond Carpets are from Brisbane Carpets, so if a Diamond Carpet isn't a Carpet Python, neither should be the South Western Carpet, or many other Carpet Pythons.

Couldn't agree more. I think what confuse many of these issues is the artificial tags that we apply to these species. To use another bird example, most of us can recognise the common galah. How many can recognise the 3/4/5 subspecies of galahs? If the northern subspecies, E.r.kuhli had been traditionally called the Pygmy galah and this name became part of widespread usage then we would automatically consider it to be more different from the nominate galah subspecies than say he western Australian subspecies is. We focus on the diamond python because we gave it a unique name that has stuck. If we originally called it a diamond carpet then thats what we would be calling it today.

 

[zen]

Wow, things have really raced along since I edited my last post.
Great stuff guys.
Very interesting and valid points everyone.

So glad that we can discuss this complex & often hairy topic with so much intelligence & maturity.

 

[JeffHardy]

It seems that this argument just confuses the hell out of everyone to the extent that arguments in this current thread are basically arguing whether or not there is none, one or a dozen subspecies of Carpet Python on the east coast and beyond.

Why can't this issue be settled once and for all by taxonomists making a serious attempt at defining what are, and are not, subspecies by using modern technology - DNA profile variation. Is there no value in this research? I suspect that they'd find that there are no (isolated) DNA defined sub-species, but rather a gradual, almost imperceptible and continuous geographic variation within the same species not only up the east coast and west across the top-end, but also inland and to the south-west of the continent.

From the keeper/breeder perspective most seem to want to describe their morph by geographic description. But then again there are an ever increasing group that have to create their own colour and pattern hybrids and mutants - some of these people seem to be driven by a perceived divine right to create new varieties that nature can't produce (because of geographic separation or some of the mutations simply would not survive to breed in the wild) and others seem to be driven primarily by potential monetary return.

From a conservation perspective the desire should be to ensure that natural variation across natural ranges is maintained by presevation of natural habitat and populations.

Irrespective of motives, I think that everyone would like to see a definitive answer to this perennial question.

 

[geckodan]

Why can't this issue be settled once and for all by taxonomists making a serious attempt at defining what are, and are not, subspecies by using modern technology - DNA profile variation

Bring it on!!. But who is going to pay for this. Certainly not any government department who's legislation still does not recognise the existence of any subspecies (QLD).

 

[herptrader]

I have preferred the term "race" to describe the different sub species of carpet pythons. Just as we have negros and caucasion humans we also have diamond and carpet morelia spilota.

People talk about language as if it was a static and fixed entity and it is not. It is continuously evolving like many other things. If we as herpers decide to use a certain term to mean a certain thing then all well and good. Another group might choose to place a slightly different meaning on a given word. If we settle on a specific definition and use the word to mean that then that is what it will mean.

Looking at the word intergrade - "Inter" means between and "grade" implies a measured element as in gradual or graduated. In this context I have no problem with integrade meaning species that show gradually different morphology over there range between to quite visually destinct races of carpet python.

 

[jordo]

There is more or less continuous gene flow right along the east coast. It's like shades of grey in some cases

Thats exactly what i meant - that there are differences in the carpets but that they can't be clearly divided.
Sorry for not being clearer, now i'm going to leave before i hurt myself :lol:

 

[Hickson]

I've argued this point several times before in different threads, so I'm not going to discuss it again. I will, however put up my view (and this is the way we've been using it in the zoo world for years):

Hybrid: offspring of two different species
Intergrade: offspring of two different subspecies (whether occurring naturally or under controlled conditions).




Hix

 

[peterescue]

The meaning of a word is not constant. It means different things in different fields.
Sophistcated metals are alloys, sophistaicated ladies were of mixed perantage. Sophisticated nowadays means something else completely.
A theory in evolution is a law where a theory in other fields isnt.
An intergrade in NSW NPWS system is a locality M. spilota ssp but in other fields is something else.
Thats the thing about language. It also isnt constant. The only thing constant is that it changes constantly.
Next week we will be discussing semiotics.
this > 0 < is a tree.

 

[peterescue]

**********COMING SOON***********
WHY I LIKE/HATE CATS.

Bookings available from the usual outlets

 

[bigguy]

This debate rears its ugly head every 6 months or so, and I am amazed why people have problems grasping what intergrades truly are compared to hybrids.

Lets start with Hybrids first as they are the easiest to explain. A hybrid is where a species, and or a sub species is bred with a different species and or sub species. This mainly occurs in captivity, but on rare occasions can happen in the wild.

Now for intergrades. There are 2 python complexes in Australia where intergrades occur. They are Carpet and Children Pythons. As these two species spread across Australia they took on different colour forms due to envirmental, geographical or climatic changes. Not so long ago most Carpets and Childrens were lumped together as a single species. Due to the work of several taxominist these were divided into subspecies.

So now with Carpets we have Irian/PNG, Top Ends, Jungles, Coastals, Inlands and Diamonds. DNA has shown all of these to be the same species, but with enough suttle differences to warrant sub species status. Centralians and South Western Carpets, due to being isolated from the eastern forms are now very different by DNA standards

With Childrens we now have Spotted, Childreni, Stimsons and Anthills. Again DNA has shown differences between each subspecies.

Now for intergrades. These are not as most people think where say a Diamond mated with a Carpet in the wild. These are actually the missing link as one sub species changed into another due to some geographical, climatic or enviromental reason. Remember, they are all the same species but changed in areas for different reasons.DNA tests have shown intergrades have again suttle differences compared to the two species they seperate

Where ever you find the range of 2 subspecies meeting, you will have intergrades in the buffer zone. If anyone ever takes the time to drive across the base of Cape york you will see this for yourself. There are 3 species of Childrens found along the road from Normington to Innisfail. However you will find 5 colours forms, due to 2 different intergrade zones. Starting from the west you 1st find Childreni, then Childreni/Stimson intergrades, then Stimsoni, then Stimsoni/Spotted intergrades and finally Spotteds.

 

[NCHERPS]

I've argued this point several times before in different threads, so I'm not going to discuss it again. I will, however put up my view (and this is the way we've been using it in the zoo world for years):

Hybrid: offspring of two different species
Intergrade: offspring of two different subspecies (whether occurring naturally or under controlled conditions).




Hix

I agree with Hix on this one.

Neil

 

[MrBredli]

Intergrade - zoology - to be transformed from one form to another through a series of stages or forms that involve partial transitions

Intergrade refers to a change that takes place over time. Putting a Diamond and a Darwin in a cage together for a couple of weeks will not result in intergrades, it will result in hybrids!