Is the skink losing legs or gaining them?

Everything Blue Tongues! Have a question? Just got a BTS and want to introduce yourself? This is the place!
Forum rules
In this forum all are welcome to ask blue tongue skink-related questions, share information, ideas, tips, experiences, and pictures with fellow BTS enthusiasts.
If you are wondering if your BTS is acting normally or might be sick, this is where you can get help with that.
This is also where you can have some FUN while sharing the enjoyment you get from your blueys!
tignish99
Tenderfoot
Tenderfoot
Posts: 29
Joined: Sun Sep 08, 2013 5:12 am
Country:
Location: Canada

Is the skink losing legs or gaining them?

Postby tignish99 » Mon Jan 06, 2014 12:27 pm

Hello. I am curious on people's opinions on where on the evolutionary ladder the skink is. They seem to be halfway between snakes and lizards as they share the characteristics of both. Do you think they are gaining their legs or losing them? I know some snakes used to have legs and still have little buds.

Please , I really do not want this to turn into an evolution debate. I am just curious what people think scientifically about these animals.

Thank you
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 12:38 pm

They are ceasing length. Australia was thought to be one big rainforest many, many, many years ago, not mostly dry (or should I say "non-rainforest-y") like it is today. So, considering how long legs of T. gigas are and how they come from the rainforest, putting two and two together, the ancestor of the Australian Bluetongues had long legs like T. gigas do now. Now since deforestation/desertification is occuring, they are ceasing leg lengths, as they are not needed since only plant matter is available most of the time in the desert.

The further you go away from the rainforest (the more you go into the desert), the short their tails are, as well.
Last edited by Dakota on Mon Jan 06, 2014 1:05 pm, edited 2 times in total.
"The love for all living creatures is the most noble attribute of man." — Charles Darwin
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 1:04 pm

Hi - I moved this out of the Advanced section because it isn't really a scientific discussion... answers including 'from what i was told', 'thought to be' etc don't belong in the ADF either, we should have some kind of references before making assumptions or answering questions with certainty. :wink:

This site: http://www.reptile-database.org/db-info/taxa.html might help you with some of your questions and just searching 'phylogeny' might help you understand how this all works. Amphisbaenia (legless lizards) are in an entirely different clade from Scincidae. There isn't any reason to believe that skinks are an intermediate form between lizards and snakes and therefor are evolving into one or the other - that isn't how it works. But that link and just googling phylogeny should help understand it a bit more! :)
tignish99
Tenderfoot
Tenderfoot
Posts: 29
Joined: Sun Sep 08, 2013 5:12 am
Country:
Location: Canada

Re: Is the skink losing legs or gaining them?

Postby tignish99 » Mon Jan 06, 2014 1:19 pm

Katrina wrote:Hi - I moved this out of the Advanced section because it isn't really a scientific discussion... answers including 'from what i was told', 'thought to be' etc don't belong in the ADF either, we should have some kind of references before making assumptions or answering questions with certainty. :wink:

This site: http://www.reptile-database.org/db-info/taxa.html might help you with some of your questions and just searching 'phylogeny' might help you understand how this all works. Amphisbaenia (legless lizards) are in an entirely different clade from Scincidae. There isn't any reason to believe that skinks are an intermediate form between lizards and snakes and therefor are evolving into one or the other - that isn't how it works. But that link and just googling phylogeny should help understand it a bit more! :)


Thank you for the info. Sorry to put it into the wrong section. I was kind of torn because it is not really scientific, as you point out, but not really a regular care question either.

I will read the link you provided. Good food for thought.
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 1:36 pm

No problem - I was moving it more because of the responses / discussion you will likely get rather than the question. Answers like 'ceasing length' due to 'what I'm told' aren't scientific and the ADF rules are pretty clear that that isn't our intent. I'm not sure there is much many people can add to a discussion unless they are working in evolutionary biology...
User avatar
Richard.C
Kimberley Klan
Kimberley Klan
Posts: 10475
Joined: Mon Oct 10, 2005 3:37 am
Country:
Location: melbourne australia

Re: Is the skink losing legs or gaining them?

Postby Richard.C » Mon Jan 06, 2014 1:41 pm

Not all blueys hail from the desert in australia,and theres not really any huge difference in leg length between varios forms that suggests desert occuring forms legs are shrinking

Centralians would have smallest legs,there probably the least vegetarian and suprisingly quite agile at chasing live food down

But when u compare say westerns to blotchies,the desert dwelling westernhas longer and solider legs to the temperate and quite riparian occuring blotch or even eastern

Fossil bluetongue ancestors have been found innorth qld which are similar in build to todays living species,not a long legged freak of the past

Not sure skinks are halfway between snakes and lizards,they appear all lizard to me
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 1:42 pm

Katrina wrote:This site: http://www.reptile-database.org/db-info/taxa.html might help you with some of your questions

How is the link provided answering her question, Kat?

And I love that Eastern in the Tiliqua gigas subsection.. :wink:
"The love for all living creatures is the most noble attribute of man." — Charles Darwin
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 1:52 pm

Dakota wrote:The further you go away from the rainforest (the more you go into the desert), the short their tails are, as well.


:shock: Ceasing legs and tails? That's not very snake like!

Morphological adaptations to deal with a desert environment do not mean that they are still evolving or that snakes are the logical end point. If there is no advantage to having shorter legs or tails than they already have, then they will remain the same. However, if there is an advantage to having shorter or longer legs then those individuals that are born with mutations that give them shorter / longer legs / tail should survive and reproduce better. But just because you see some morphological differences between scindicae in different environments doesn't mean that they are 'interim' creatures that are moving towards some predetermined end point (such as losing legs completely).

Snakes aren't any further along evolutionarily than lizards - they just branched off at different times. Same with skinks - they may look 'in between' but they aren't an interim creature. Hopefully that explanation makes some sense.
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 1:53 pm

Richard.C wrote:Not all blueys hail from the desert in australia,and theres not really any huge difference in leg length between varios forms that suggests desert occuring forms legs are shrinking

Centralians would have smallest legs,there probably the least vegetarian and suprisingly quite agile at chasing live food down

But when u compare say westerns to blotchies,the desert dwelling westernhas longer and solider legs to the temperate and quite riparian occuring blotch or even eastern

Fossil bluetongue ancestors have been found innorth qld which are similar in build to todays living species,not a long legged freak of the past

Not sure skinks are halfway between snakes and lizards,they appear all lizard to me

My response was in theory. :) So this isn't taking in account of perhaps a population of insects or mice that have adapted well with the desertification, causing an abundant population to where the Lungata would not have to travel far (reason why legs are still short), but keeping the agility.. maybe?

Food for thought.

At Kat, I did not say they were turning into snakes.. only the OP mentioned that. I gave no thought to that part of the question.
"The love for all living creatures is the most noble attribute of man." — Charles Darwin
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 2:01 pm

Dakota wrote:
Katrina wrote:This site: http://www.reptile-database.org/db-info/taxa.html might help you with some of your questions

How is the link provided answering her question, Kat?


What do you mean? It clearly shows how snakes, skinks and legless lizards relate to each other phylogenically.
tignish99
Tenderfoot
Tenderfoot
Posts: 29
Joined: Sun Sep 08, 2013 5:12 am
Country:
Location: Canada

Re: Is the skink losing legs or gaining them?

Postby tignish99 » Mon Jan 06, 2014 2:15 pm

Dakota wrote:
Richard.C wrote:
At Kat, I did not say they were turning into snakes.. only the OP mentioned that. I gave no thought to that part of the question.


Sorry, if it sounded as if I was saying they are turning into snakes. That is not the case. I was just wondering where on the evolutionary ladder they are and what people thought was going to happen to their bodies. I am aware of how evolution works, and I was just wondering what other people thought about the evolutionary future of the skink.
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 2:18 pm

Katrina wrote:
Dakota wrote:
Katrina wrote:This site: http://www.reptile-database.org/db-info/taxa.html might help you with some of your questions

How is the link provided answering her question, Kat?


What do you mean? It clearly shows how snakes, skinks and legless lizards relate to each other phylogenically.

He/She asked if they were gaining or losing leg length, she stated they they seem to be halfway between snake and lizard.
"The love for all living creatures is the most noble attribute of man." — Charles Darwin
User avatar
Richard.C
Kimberley Klan
Kimberley Klan
Posts: 10475
Joined: Mon Oct 10, 2005 3:37 am
Country:
Location: melbourne australia

Re: Is the skink losing legs or gaining them?

Postby Richard.C » Mon Jan 06, 2014 2:23 pm

Hmmm,lots of desert skinks have long tails and legs,someone must have forgotten to tell them they need to start losing tail and leg length,mind you if a king skink says no you dont argue,lol

Centralians legs look short as they are fat bodied,they walk alot holding body off the ground,and have tiny feet,adaptations believed to move about on hot sand/substrate,they are oddballs,suprisingly quite agile,there habitat is probably one of the worst in regards to vegetaion available for consumption
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 3:17 pm

tignish99 wrote:Sorry, if it sounded as if I was saying they are turning into snakes. That is not the case. I was just wondering where on the evolutionary ladder they are and what people thought was going to happen to their bodies. I am aware of how evolution works, and I was just wondering what other people thought about the evolutionary future of the skink.


I don't think we can answer that for Tiliqua as a whole or Scincidae as a whole - it really depends on the environment that they are in and what is advantageous in that environmemnt. The link I provided answered the question on where on the evolutionary 'ladder' they are, but the different species are from very different environments so to say that as a whole, Tiliqua is moving towards losing their legs would be... well, not scientifically supportable is the best way to put it. A poor assumption...

There is no studies that show that any Tiliqua species are losing their legs that I can find.

There are some studies show other skinks in sub-Saharan Africa are losing their legs, and quite a few Scincidae species are legless or nearly legless (that is true for many families of lizards, not just Scincidae), but to infer from that that Tiliqua is also heading in that direction would be quite a leap. Because the entire Scincidae family branched off at the same time evolutionarily, and because now there are many species of legless lizards or nearly legless lizards in Scincidae, I think it would be fair to say that if it was advantageous for Tiliqua to be legless they would have evolved that way already. Other species of skinks had ample time. So without any evidence showing Tiliqua losing legs, I think the best answer is to assume that they aren't losing their legs (but they aren't really 'gaining' them either). It goes back to what I said about them not being an 'intermediate' species moving in one direction.

In future, changes to their environment may make it advantageous to either lose their legs or to have longer legs. But right now they seem stable, I can't find any evidence of them moving in either direction. Of course, this is talking about very large timelines - so we may not have enough information to answer that.

I am no expert in evolutionary biology, I've just taken several university classes - so this is just my best guess / answer. Because many other members of the skink family have already lost their legs or are in the process of it, if Tiliqua were losing their legs I think we would have evidence of it. With no evidence, I would assume that they are not gaining or losing legs, so to speak.
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 3:21 pm

Katrina wrote:I don't think we can answer that for Tiliqua as a whole or Scincidae as a whole - it really depends on the environment that they are in and what is advantageous in that environmemnt. The link I provided answered the question on where on the evolutionary 'ladder' they are, but the different species are from very different environments so to say that as a whole, Tiliqua is moving towards losing their legs would be... well, not scientifically supportable is the best way to put it. A poor assumption...

There is no studies that show that any Tiliqua species are losing their legs that I can find.

There are some studies show other skinks in sub-Saharan Africa are losing their legs, and quite a few Scincidae species are legless or nearly legless (that is true for many families of lizards, not just Scincidae), but to infer from that that Tiliqua is also heading in that direction would be quite a leap. Because the entire Scincidae family branched off at the same time evolutionarily, and because now there are many species of legless lizards or nearly legless lizards in Scincidae, I think it would be fair to say that if it was advantageous for Tiliqua to be legless they would have evolved that way already. Other species of skinks had ample time. So without any evidence showing Tiliqua losing legs, I think the best answer is to assume that they aren't losing their legs (but they aren't really 'gaining' them either). It goes back to what I said about them not being an 'intermediate' species moving in one direction.

In future, changes to their environment may make it advantageous to either lose their legs or to have longer legs. But right now they seem stable, I can't find any evidence of them moving in either direction. Of course, this is talking about very large timelines - so we may not have enough information to answer that.

I am no expert in evolutionary biology, I've just taken several university classes - so this is just my best guess / answer. Because many other members of the skink family have already lost their legs or are in the process of it, if Tiliqua were losing their legs I think we would have evidence of it. With no evidence, I would assume that they are not gaining or losing legs, so to speak.


Wow, good outlook/answer/opinion on the question! :)
"The love for all living creatures is the most noble attribute of man." — Charles Darwin
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 3:23 pm

Dakota wrote:My response was in theory. :) So this isn't taking in account of perhaps a population of insects or mice that have adapted well with the desertification, causing an abundant population to where the Lungata would not have to travel far (reason why legs are still short), but keeping the agility.. maybe?

Food for thought.


This makes no sense... I'm not sure what you are getting at. Same with your earlier answer - to assume that Tiliqua is 'ceasing' legs (ceasing isn't the right word in this case, by the way) because Australia is a desert makes no sense because not all desert reptiles lack legs. If all tropial species had legs and all desert species had no legs then you might be able to infer that Tliiqua in desert environments will eventually lose their legs. But that isn't the case. There are legless lizards and snakes in tropical environments as well as desert environments, same as their are legged lizards in both.

Insects and rodents exist in desert environments too...
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 3:35 pm

To me, it does make sense.

I was going to comment this earlier, but got busy bringing the skinks in for the night.. buuuuut:

There are many other factors in it (availability of prey, native prey/predator, climate, ect., ect.), but to me it all boils down to the fact they are in a less "tropical" environment.

I do not have a degree in evolutionary history, as well as I do not have one in English.

And to your opinion on saying they are not gaining/losing leg length, I would say invalid, now that I think on it. Tiliqua gigas originated from their Australian counterpart by traveling to Papua due to low water-level all that time ago (which it states in the bluey bible), so they pretty much look like Easterns when they first made their way there, correct? If they were not changing, they would still have stubby limbs/tail, but they do not, they evolved to be longer.

In a sense to looking at it, they could also be gaining it over a long period of time. I guess it all depends on which side you look at.. the ones going North.. or the ones going South.
"The love for all living creatures is the most noble attribute of man." — Charles Darwin
User avatar
Katrina
The Daredevil
The Daredevil
Posts: 9767
Joined: Sun Dec 02, 2007 3:34 pm
Country:
Location: Alberta, Canada

Re: Is the skink losing legs or gaining them?

Postby Katrina » Mon Jan 06, 2014 4:16 pm

Dakota wrote:They are ceasing length.

Dakota wrote: In a sense to looking at it, they could also be gaining it over a long period of time.

Dakota wrote:And to your opinion on saying they are not gaining/losing leg length, I would say invalid, now that I think on it.


Ok - I'm still a bit confused as to your point... You are saying that they are 'ceasing' length or could also be gaining length, but my opinion is invalid? And what is your reasoning?

I'm not trying to argue, I just honestly can't understand what your point of view is.

Yes, Tiliqua gigas has longer legs / tails than Tiliqua scincoides. BUT - how can you prove that they are still getting longer? Or that Tiliqua scincoides limbs are getting shorter? Or that desert species of Tiliqua are getting shorter over time? Maybe their legs / tails are at the right length for their current environment / diet and aren't changing appreciably either way... that is my argument, based on the fact that if short or no legs was an advantage for them they would have had ample time to become legless. Yes, there are morphological differences amongst the species of Tiliqua. But I don't see any reason to assume that either Tiliqua as a whole or species of Tiliqua as a whole have legs that are getting longer or shorter.
User avatar
donkeybuff
Coffee Connoisseur
Coffee Connoisseur
Posts: 1591
Joined: Sat Jan 07, 2012 8:56 pm
Country: USA
Location: California

Re: Is the skink losing legs or gaining them?

Postby donkeybuff » Mon Jan 06, 2014 4:26 pm

Katrina's right on this one. There's not really any substantial evidence other than "I feel that this is happening" that there is currently a selection pressure for longer legs in some regions and shorter legs in others. It is possible that Tiliqua Gigas faced a selection pressure that favored specimens with longer legs in the past, but that selection pressure may not apply today. Just because they now have longer legs than, say, Centralians doesn't mean that their legs are still getting longer while Centralians' legs are getting shorter.
Sachin
1.0 Indonesian
1.0 Northern
User avatar
Dakota
Snail Hunter
Snail Hunter
Posts: 5208
Joined: Fri Mar 01, 2013 3:30 pm
Your Facebook name: Dakota Nivens
Country: US

Re: Is the skink losing legs or gaining them?

Postby Dakota » Mon Jan 06, 2014 4:28 pm

I'm not sure about now, but between the time the first skinks reached Papua and now, their legs lengths have gained.

And by ceased, I mean decreased, my apologies.

But when you look at the Aussie skinks, compared to their ancestor, they have shorter limbs.
"The love for all living creatures is the most noble attribute of man." — Charles Darwin

Return to “General Discussion and FAQ”

Who is online

Users browsing this forum: Bing [Bot] and 2 guests