Carpet python systematics shock ...

[toxinologist]

Hi all,

In response to a question about carpet python Morelia spp systematics in a PM today I gave the following reply which on reflection might interest quite a few people here:

The latest work on carpet pythons will raise more than a couple of eyebrows I think you'll find ...

Essentially Taylor et al reported to the 2003 ASH Conference that analysis of mtDNA control region sequences, 22 allozyme loci and eight microsatellite loci from 350 snakes sampled from 119 locations throughout the range of the complex in Australia and New Guinea demonstrated (with good correlation between all three techniques) that there ARE ONLY THREE VALID TAXA IN THE COMPLEX ... :shock:

These being:

Morelia bredli (Central Australia)
Morelia spilota imbricata (South-western WA/Eyre Peninsula)
Morelia spilota spilota (All eastern and northern forms)

The abstract reference is

Taylor D, Rawlings L, Donnellan SC, Goodman AE. (2003) Population structure of the highly polytypic Australian carpet pythons (Reptilia: Morelia spilota) Proceedings of the 2003 Meeting of the Australian Society of Herpetologists.

The actual paper will probably be in print sometime this year.

I imagine that this will come as a big shock to a lot of folks - no more M.s.variegata, M.s.cheynei, M.s.mcdowelli etc etc ....

Cheers


David

 

[instar]

Thats really intresting stuff mate, Maybe regional varience in pattern/ size can be soley put down to climatic difference and enviromental difference. Guess a carpet is a carpet ! but then to me, a horse is just a horse! lol

 

[NoOne]

Not that it's going to make much difference people are still going to call them what they are.
Tell me theres no difference between cheynei and spilota spilota, i don't care what DNA says.

 

[Fuscus]

Must be using the "Fingerprint" model where they just compare certain points along the DNA chain

http://www.nature.com/nsu/030512/030512-7.html

mtDNA is only part of the picture, its a bit dicey to base the entire analysis on this. I also get a bit cynical when someone claims 99.9999% sucess.

Still doesn't change my typing of people who name animals, they are either Lumpers or Splitters.

 

[toxinologist]

NoOne,

Studies of DNA establish whether or not a group of animals belong to one taxonomic unit (a genetically distinctive unique lifeform) or to two or more taxonomic units. Each taxonomic unit bears a single taxonomic designation - a name.

Taylor et al's work is strong evidence for concluding that all of the eastern Australian and northern Australian Morelia belong to just one taxonomic unit Morelia spilota spilota. Sure some of them look different - that means nothing.

Look at it this way ... Unless they happen to be biggotted, racist, s@*mbag hitlerites :twisted: most people accept that the human race is comprised of a single taxonomic unit Homo sapiens with wide geographical variation in appearance but just one unique genome. The concept is simple, broadly accepted and proven fact.

So why should it be so hard to accept the fact that in terms of many other types of animals similar variations in appearance (for whatever reasons)... such as colour, body size ... occur despite the fact that the genome of all is one and the same.

This doesn't mean you can't keep referring to different forms by their regional colloquial names: 'jungles', 'diamonds', 'brissies', 'coastals' or whatever ... it just means that from a scientific name perspective they are all just going to be Morelia spilota spilota.

And I can tell you this...

The managers of our wildlife resources will accept this sort of scientific evidence, and use it in the management of the fauna. And whether herpetoculturalists like it or not they will just have to get used to a much simplified nomenclature.

Those are the facts, and as more and more reliable DNA technology is developed and applied to these issues, expect more changes.

Cheers


Dave

 

[toxinologist]

Fuscus,

In this case, these guys have used THREE different techniques with a broad sample from many different locations in both Australia and PNG; and all three techniques gave the results that agreed with one another ...

Cheers


Dave

 

[Fuscus]

Looks like it is not just carpets. This is a proposal to do the same study with American milk snakes.
http://www.kbrin.louisville.edu/about/zimmerer.html
the key line is
"This proposal is an attempt to answer these questions using a set of molecular characters. These characters are mtDNA sequences that have been shown in other groups to be largely invariant within groups but differ between groups."

So what they are proposing is determining the animals status by only looking at certain sequences.

 

[Simon_Archibald]

With all of the talk lately of crosses/hybrids/designer pythons, this thread raises an interesting point. NPWS have big issues obviously breeding different subspecies even together (eg. breeding a cheynei with a metcalfei, etc, etc). If all these species appear on our licences in a few years time as Morelia spilota spilota, will we not see heaps and heaps of people crossing because they will then be able to put them in their licence record books as legitimate???

Scary thought...

Simon Archibald

 

[toxinologist]

G'day Simon,

More to the point these 'forms' of Morelia spilota spilota being all the same species will in fact be perfectly legal to cross/hybridize/design - after all they are one and the same species - the only think stopping breeding in the wild is geography.

As to whether mixing geographically isolated popuations with one another is right or wrong ... herpers have been doing that with other less distinctive geographic forms for years ... take 'spotted phase' and 'blue phase' Pseudechis guttatus for example, or even just specimens of Aspidites melanocephalus sourced from different breeders in different States ... the end results (a mixed genetic product of two geographically isolated specimens) are still the same.

Cheers


Dave

 

[Fuscus]

Dave, I'm not doing this just to argue and I can see that I might be looking bad, I am just trying to understand and/or explain the process. Intuition says that if an animal is both a different size and colorization then it must be a a diferent type. But intuition is not always right. Carpets are like humans, highly varible with wide geographical variation in appearance (Personally, I like it this way, the world would be boring if we were al the same)
I also realize that the process of using certain sequences is the only practable way to do this type of study.
But this brings me back the the age-old question - what constiutes a species or sub species? :?

 

[Simon_Archibald]

David,
I do agree with you about what is already happening within different species. It has been happening for ages. Also, I know it will be perfectly legal when they are described as one species, I just think it will be interesting to see what people do in reaction. Maybe we'll have the die-hard breeders selling "locality-based" species, still hanging onto names like Murrays, Coastals, Jungles, etc. Then you'll have people who are into the designer side of it and mix any with all.

It will be a crazy explosion me thinks.....

Simon Archibald

 

[toxinologist]

G'day mate,

The general simplified concensus is that a species is a group/population that are naturally occurring and which can reproduce with one another to produce viable fertile offspring.

Genetics (a relatively new science) introduces many new ways of looking at this, and there are a number of 'concepts of species' floating around; i.e.: the biological species concept and the genetic species concept are two well-known and much debated ideologies (just punch these terms into Google for hours and hours of frustratingly conflicting discussions... :wink: )

Studies such as Taylor's that use a variety of genetic methods to try and answer species questions are helpful in that they provide strong evidence that has the advantage of being reproducible. The probabilities that an unrelated taxa will have the same sequence alignments are extremely small, and this provides hitherto unheard of levels of confidence in either accepting or rejecting hypotheses about species relationships. And the great thing about it is the results are reproducible - a person on the other side of the world can align the sequence from an animal they have with the published sequence (via the internet!) and make meaningful scientifically sound comparisons - effectively determining the identity of the snake they are holding.

The old ways of identifying animals from scale counts, colour pattern, dentition etc still has an important role - DNA evidence should be supported by quality morphometric analyses - but written descriptions of colour for example are open to misinterpretation, scale counts within even two snakes from the same clutch can vary considerably, etc.

DNA sequences within a single species do not vary to a significant degree - when the sequences do vary significantly - you tend to be looking at different species. :lol:

Personally I feel very comfortable accepting genetic studies that are based on good sampling, broad geographic sampling and where possible - meaningful analyses of broader morphological data.

Cheers


Dave

 

[toxinologist]

Simon ...

Spot on with that outcome estimate mate!

Cheers


Dave

 

[peterescue]

The only thing about this that surprised me is that bredlii is a separate species.
And be prepared for a lot more redundancies.

Peter

 

[Fuscus]

The general simplified concensus is that a species is a group/population that are naturally occurring and which can reproduce with one another to produce viable fertile offspring.

Yeh, thats the defination I know and I think (as you proberly do) that it is too fuzzy to be of much use.

Genetics (a relatively new science) introduces many new ways of looking at this, and there are a number of 'concepts of species' floating around; i.e.: the biological species concept and the genetic species concept are two well-known and much debated ideologies (just punch these terms into Google for hours and hours of frustratingly conflicting discussions... :wink: )

LOL, the answer I feared and expected. But it does leave room for lumpers
(sequence X and Y are the same so it is the same species) and splitters (sequence X and Y are the same but Z is different so it is the different species)
And as an aside, I googled mtDNA before and ended up on a creationist site that used mtDNA to "Prove" the bibical timeline

Studies such as Taylor's that use a variety of genetic methods to try and answer species questions are helpful in that they provide strong evidence that has the advantage of being reproducible. The probabilities that an unrelated taxa will have the same sequence alignments are extremely small, and this provides hitherto unheard of levels of confidence in either accepting or rejecting hypotheses about species relationships. And the great thing about it is the results are reproducible - a person on the other side of the world can align the sequence from an animal they have with the published sequence (via the internet!) and make meaningful scientifically sound comparisons - effectively determining the identity of the snake they are holding.

The old ways of identifying animals from scale counts, colour pattern, dentition etc still has an important role - DNA evidence should be supported by quality morphometric analyses - but written descriptions of colour for example are open to misinterpretation, scale counts within even two snakes from the same clutch can vary considerably, etc.

Any links to the methods used? I agree that DNA evidence is just another tool and will get further refined as time goes by, still early days yet.

DNA sequences within a single species do not vary to a significant degree - when the sequences do vary significantly - you tend to be looking at different species. :lol:

Personally I feel very comfortable accepting genetic studies that are based on good sampling, broad geographic sampling and where possible - meaningful analyses of broader morphological data.

Cheers


Dave

IMHO the species arguement/game will still continue, its just that there is a newer playground. It will also be interesting to see what mtDNA makes of rift valley cichlids.

 

[BROWNS]

I would've guessed that diamonds would have different dna than the rest.If they aren't different at all what makes them so different with their requirements in captivity.So a jungle diamond cross is no longer a hybrid. That sure will be a hard one to come to terms with for some people.

Is there a difference in dna between the WA stimmies,bhp's and womas to their eastern counterparts?I have been told that the Pilbara bhp's have a different scale count to NT and QLD BHP'S.

 

[peterescue]

That a group of animals can breed are a species is of course a given but this doesnt mean that 2 distint species that can breed together are the same species as has been shown with several species of Australian freshwater turtles.
Peter

 

[PilbaraPythons]

Hi Browns
There is a distinct scalation difference between the eastern blackheads and our western form however I am far from convinced that this difference is consistent through out our state. I fully believe that this difference is only evident in the ones found from about lower Broome and to Whim creek. Its seems the further north east you find them the more they look like the eastern form. The form found where I reside clearly lack suboculars and have a single loreal scale. Our woma?s interesting enough share this trait. I will be working closely with three herpers spread around the far North West and will endeavor to find out where these forms change. It would be very interesting to know what David Williams thinks of Hosers discription of the blackhead here and if David will in the future be collecting dna data for comparisions. Adrian Hogg and myself believe that we may have discovered some thing very interesting in regards to the taxomony of aspidites and will reveal this after further researh and access to a laboratory. We will most probably try to get David Williams involved in this if possiable.

Cheers David Mackintosh
PILBARA PYTHONS

 

[BROWNS]

Very interesting Dave!!! I also think it will be interesting if there is a difference between Tanami,Uluru and SA womas.

Got any pics of nice black and whites you've collected Dave?

 

[PilbaraPythons]

Andrew
I will send you over a few pic's of some of our better looking blackheads and of a strange coloured stimsons.
Cheers Dave