If a newt/sal is sexable, is it sexually mature?

[jAfFa CaKe]

Hi guys, I think the title says it all. If a newt or salamander is sexable(is that a word?), is it sexually mature?
Thanks!

 

[Chinadog]

Not necessarily, It just means you can tell if it's male or female.

 

[jAfFa CaKe]

Ahhhh, okay. Thanks for clearing that up!

 

[Azhael]

Strinctly speaking no, but for the most part, yes xD
Technically you can even sex eggs, however nobody outside of a research facility has at their disposal the necessary equipment to do so. So as a matter of practicality it is almost never possible to tell the sex of an individual until the secondary sexual characteristics appear and that happens at the time when they become sexually mature so in the end it holds true that in order to be able to reliably sex a caudate, it has to be mature (or at least in the process of maturing).
There are no reliable ways of sexing them before that happens because until the secondary sexual characteristics develop, both sexes are indistinguishable by external appearance, and obviously if you open them up to look at their gonads, you kill the animal and kind of defeat the whole purpose

I should add that on very few occasions i've seen people claiming to be able to sex juveniles, but i'd be extremely skeptical of these claims, i've seen nothing that indicates that they can do so reliably. The one exception, i'm aware of, that might be somewhat reliable have been I.alpestris juveniles which seem to be slightly dimorphic.

 

[jAfFa CaKe]

That's interesting, thanks for the Rodrigo. I've read on CC that eggs can be made to become a certain sex due to temperature, I know this is present in a few lizards, but CC says an example of this 'phenomena' has been encountered in P. waltl, what would happen if you tested eggs like that? (Just to be clear, I'm not really expecting a sure answer!)

 

[Azhael]

Well, that's an interesting an complicated phenomenon. If you tested those eggs, or the resulting individuals at any point of development, the result would be whatever sex they are genetically. However, the phenotypical, or externally observable sex would be the opposite because these animals instead of developing as usual, with the characteristics of their genetic sex, develop the characteristics of the opposite sex because different genes are turned off and on.
P.waltl for example has a ZZ/ZW chromosome system like we have XX/XY, but the difference is that while there are some differences, both choromosonal types contain all the necessary information to make a complete, fertile female, so a genetic male, through the activation and inactivation of different genes can develop into a fertile female.
It gets reaaaaallly complicated, but that's the gist of it. I hope that was helpful xD

 

[jAfFa CaKe]

Thanks! XD

 

[sde]

I should add that on very few occasions i've seen people claiming to be able to sex juveniles, but i'd be extremely skeptical of these claims, i've seen nothing that indicates that they can do so reliably. The one exception, i'm aware of, that might be somewhat reliable have been I.alpestris juveniles which seem to be slightly dimorphic.

I have read on CC that brightly colored juvenile Triturus marmotatus are usually females. Is this a reliable way to sex juveniles of this species?

 

[Azhael]

I'm personally not convinced that this is reliable. The thing is that when you only have two options, it's quite easy to get it right by pure chance every now and then and we humans are very good at confirmation bias, that is remembering the times we got it right and forgetting all the times we got it wrong.
There may be something to it but i would not consider it a reliable sexing technique for the species as a whole. The only examples of using such cues to sex caudates are purely anecdotal.

 

[sde]

Thanks Rodrigo.
I kind of figured that it wasn't reliable, since intensity of color can also be effected by diet.
I agree with what you said about bias, unfortunately it's only human to do so.
Just out of curiosity, what are the "slightly dimorphic" differences between I. alpestris juveniles? And does it only apply to I. a. alpestris or to the subspecies as well?

 

[Chinadog]

I should add that on very few occasions i've seen people claiming to be able to sex juveniles, but i'd be extremely skeptical of these claims, i've seen nothing that indicates that they can do so reliably. The one exception, i'm aware of, that might be somewhat reliable have been I.alpestris juveniles which seem to be slightly dimorphic.

It was actually my I alpestris juveniles I was thinking of when I posted my reply. I was trying to sex four of them this morning that I'd sold (to jake, lol!). It's possible to see the very beginnings of the males crests and there is a difference in cloaca size, but that only means the others are either females or males that are less well developed, so it's not that reliable I suppose!