Oxyuranus/Pseudechis group phylogeny

[waruikazi]

This is a question in regards to red bellies being ovoviviparious.

All live bearing Australian elapids are in the Oxyuranus (taipan) group. The group is split into two sub groups Oxyuranus (tais alone) and Pseudechis (blacks and all other live bearers).

All live bearing Australian elapids have undivided subcaudal scales. The tais all have divided subcaudal scales.


The only live bearing black is the the red belly. They have undivided subcaudals, no suprises. But in some photos i saw today along with a little digging, other species of blacks (maybe all??) have undivided subcaudals yet they are still egg layers.

My questions are...
Did taipans re-evolve egg laying?
Did the egg laying blacks re-evolve egg laying?
Or did live bearing evolve independantly more than once in this lineage? And if this is the case then why do all live bearers share un-divided subcaudal scales?

And why aren't red bellies in their own genus?

 

[Jonno from ERD]

G'day mate,

I'm not confident enough to answer some of those questions, but I can offer some knowledge on why Red Bellies aren't in their own genus.

They were the first of the Pseudechis genus to be described, so if the rest (P.butleri, P.guttatus, P.australis, P.colletti, P.papuanus, P.weigeli et al.) are to be separated, a new genus would need to be created. This has kind of been done before, but hasn't been accepted as, from what I understand, the descriptions didn't adhere to ICZN standards. This was originally done by Wells and Wellington in 1983/85, and has been rehashed by some lunatic in Melbourne.

Whether this will eventually become a formal split, I'm not sure - I have no idea what the genetic variance is between them.

 

[waruikazi]

Thanks Jonno,

Do you have any books that would belp?

 

[Elapidae1]

Yet to my understanding Tais are more closely related to Browns.

 

[waruikazi]

Yet to my understanding Tais are more closely related to Browns.

It all seems to depend on which book you read.

 

[butters]

There are a lot more live bearing elapids that aren't in either of those groups.
Also Adders will often show divided subcaudals, but not always,in saying that it does definitely seem to be the norm to have undivided subcaudals.

As for the RBB's as Jonno has posted because the genus was erected for them all of the others would have to be moved if there was a split.

 

[$NaKe PiMp]

wow gordo youve raised alot of very intersting questions in that one post!! i wish we had more discussions like this on this forum.
the statements about elapid evolution you will have to be careful about the sources of your information,its very easy to misinterpret or gather information that is false off google searches,it can get very confusing.

i have done alot of research especially when i was writing for the coarse i was doing ,i ended up with a document that was 30,000 words on Pseudechis porphyriacus.
one of the questions i asked my self was why is P.porphyriacus an ovivaparous species put in same genus as the other oviaparpous species in Pseudechis.
I got told a good answer from a Phd candidate who gets on this forum (username serpentes) and mode of parity can vary not only in a genus but in a single species!!
A good example is Saiphos equalis the three toe skink,depending on the locale they vary from live bearing to egg laying. I did a bit of reading about that i found it very intersting.
So P.porphyriacus taxonomy places it in genus of the other species it is closely related to genetically.
Now Raymond hoser has written all about further dividing and actually places it as the only member of the genus pseudechis if you read up on what he has written which is intersting,as the guy no doubt has an amazing knowledge of snakes but went crazy along the way somewhere lol.

so to best answer your questins you wil have to read some papers and there is a couple that come to mind straight away i can remeber which will help, the main one being this one
http://www.reptilehobbyist.com/aho/pdf/menu3/shine1987.pdf

but some more reading
http://sydney.edu.au/science/biology/shine/publications/reprints_legal/16theevolution.pdf


http://pages.bangor.ac.uk/~bss166/Publications/2004_OzElapids_MPE.pdf



37. Shine, R. 1983. Reptilian viviparity in cold climates: testing the assumptions of an evolutionary hypothesis. Oecologia 57:397- 405.

Mengden, G. A., R. Shine, and C. Moritz. 1986. Phylogenetic relationships within the Australasian venomous snakes of the genus Pseudechis. Herpetologica 42:215-229.

 

[butters]

Great links. Thanks for that.

Some sections make a great deal of sense when you look at the climate distribution of live bearing species. Live bearing seems to be the norm for many different taxa of reptiles in cooler climates.

Geckos in New Zealand, skinks in Tasmania are a prime examples.

Are RBB's livebearing because their distribution extends into cooler climates than the others or did they expand there because they were already were and it favoured their expansion?



Every possible explanation as to why brings up its own set of questions but doesn't really give any definitive answers.

There are numerous tropical taxa of reptiles that are live bearing.

 

[grimbeny]

Giving birth to live young has evolved an extremely high number of times (more than 120 in vertebrates, with most of these being in squamate reptiles). There are definatly examples where it has evolved independently in very closely related groups. I admit all of my understanding on this topic comes from skink litterature, but I would not be suprised in any way if viviparity has evolved independantly in Tais and black snakes.

There are a few theories which try to explain why it is advantageous. The cold climate hypothesis is not the complete story.

Ovoviviparous is not a term that is used anymore in the litterature, it is too ambigous so people call species either viviparous or oviparous.

Linneages do not revert to oviparity after evolving viviparity.

 

[waruikazi]

There are a lot more live bearing elapids that aren't in either of those groups.
Also Adders will often show divided subcaudals, but not always,in saying that it does definitely seem to be the norm to have undivided subcaudals.

As for the RBB's as Jonno has posted because the genus was erected for them all of the others would have to be moved if there was a split.

Not according to the phylogenetic tree in Greer Et al, 1997. Also according to this tree they are the same group but have been split into two sub-groups. Unless we consider the Hydrohpidae family. Even then the literature i have read (i'll concede isn't alot and i'm basing it mainly on Greer) says that the group of terrestrial elapids that they are most similar to is the group that includes Notechis. Which are in the Oxyuranus group and Pseudechis sub-group.

I can't remember where i read it but i remember that tigers, along with death adders, can have divided sub-caudals. But the norm is that they are fused.

wow gordo youve raised alot of very intersting questions in that one post!! i wish we had more discussions like this on this forum.
the statements about elapid evolution you will have to be careful about the sources of your information,its very easy to misinterpret or gather information that is false off google searches,it can get very confusing.

i have done alot of research especially when i was writing for the coarse i was doing ,i ended up with a document that was 30,000 words on Pseudechis porphyriacus.
one of the questions i asked my self was why is P.porphyriacus an ovivaparous species put in same genus as the other oviaparpous species in Pseudechis.
I got told a good answer from a Phd candidate who gets on this forum (username serpentes) and mode of parity can vary not only in a genus but in a single species!!
A good example is Saiphos equalis the three toe skink,depending on the locale they vary from live bearing to egg laying. I did a bit of reading about that i found it very intersting.
So P.porphyriacus taxonomy places it in genus of the other species it is closely related to genetically.
Now Raymond hoser has written all about further dividing and actually places it as the only member of the genus pseudechis if you read up on what he has written which is intersting,as the guy no doubt has an amazing knowledge of snakes but went crazy along the way somewhere lol.

so to best answer your questins you wil have to read some papers and there is a couple that come to mind straight away i can remeber which will help, the main one being this one
http://www.reptilehobbyist.com/aho/pdf/menu3/shine1987.pdf

but some more reading
http://sydney.edu.au/science/biology/shine/publications/reprints_legal/16theevolution.pdf


http://pages.bangor.ac.uk/~bss166/Publications/2004_OzElapids_MPE.pdf



37. Shine, R. 1983. Reptilian viviparity in cold climates: testing the assumptions of an evolutionary hypothesis. Oecologia 57:397- 405.

Mengden, G. A., R. Shine, and C. Moritz. 1986. Phylogenetic relationships within the Australasian venomous snakes of the genus Pseudechis. Herpetologica 42:215-229.

Thanks for that! Great readings. Could only manage one before my eyes started to bleed from the fuzziness though :lol:! I'm usually very dubious of anything i read on the net and i did try to read some of Hosers' papers. But then i found about 3 papers all discrediting the majority of his work lol. Hard to take someone serious when you see that.

What i am most curious about is why live bearing has occured only within this group (according to my reading) of Australian terrestrial elapids.

 

[grimbeny]

Shine's Australian Snakes shows the Australian elapids have evolved viviparity twice independently. Once in the ancestor to Death adders, tiger snakes sea snakes etc. and once in the the common black snake.

Im not quite sure which group you are reffering to Gordo but asking why no other groups have evolved viviparity might be a bit like asking why primates havnt evolved sonar.

I think Crespi & Semeiuk (2004) is probably the most interesting paper regarding the evolution of viviparity, but im not sure that it will answer your questions.

Crespi, B., and C. Semeniuk. 2004. Parent-Offspring Conflict in the Evolution of Vertebrate Reproductive Mode. The American Naturalist 163: 635-653.

 

[waruikazi]

Shine's Australian Snakes shows the Australian elapids have evolved viviparity twice independently. Once in the ancestor to Death adders, tiger snakes sea snakes etc. and once in the the common black snake.

Im not quite sure which group you are reffering to Gordo but asking why no other groups have evolved viviparity might be a bit like asking why primates havnt evolved sonar.

I think Crespi & Semeiuk (2004) is probably the most interesting paper regarding the evolution of viviparity, but im not sure that it will answer your questions.

Crespi, B., and C. Semeniuk. 2004. Parent-Offspring Conflict in the Evolution of Vertebrate Reproductive Mode. The American Naturalist 163: 635-653.

The group i am referring to is the group i made this thread about, Oxyuranus.

Don't be stupid! It's not like asking that at all and that is not what i asked. I asked 'why live bearing has occured only within this group (according to my reading) of Australian terrestrial elapids.'

If you read my first post you will see that, according to the phylogentic tree that i have access to, all of the live bearers are within the one group. I find it curious that it may have evolved twice independantly within this group and particularly why within the Pseudechis sub-group.

I have Shine's book that you are referring to and i don't think it shows that at all. It makes a statement that live bearing has occurred independantly twice but it doesn't reference anything, which is a problem i have with this particular book. What Shine's book doesn't tell you is that tigers, death adders, bardicks etc etc are all in the same group and sub-group ('lineages') as the black snakes.

So far the best book i have found that addresses the evolution of Australian elapids is The Biology and Evoluition of Australian Snakes by Allen Greer 1997. It is old but it is all i can find. Curiously it begs the same questions that i asked in my initial post.