Newt Neoteny

[a.]

What conditions encourage a newt to become neotonic in the wild / nature? Had anyone ever had noetenic newts (what species and conditions)?
Are some newt species / bloodlines more prone to neoteny than others?

 

[ryan]

A newt or any salamander that assumes neotany in the wild is usually because the land environment is unfavorable but other times it just happens like unnatural colors (albino). I'm no expert but that is what I have read.

 

[kara]

tiger salamnders can become huge neotonic adults, there is a neat picture of this on the species page of ambystoma tinigrum

 

[abrahm]

Livingunderworld.org has an excellent article on caudate biology (as well as the other Orders of Amphibia.) In the third paragraph of this article can be found information on neoteny in caudates.

<blockquote><hr size=0><!-quote-!><font size=1>quote:</font>

Neoteny, sometimes called paedomophism, is apparent in all caudate families except Rhyacotritonidae.<!-/quote-!><hr size=0></blockquote>

It then goes on to say that facultative neoteny occurs due to environmental factors. It may also be influenced by genetics.

 

[a.]

Thank you all for answering. Still no specific info as for exactly what environmental conditions are 'responsible' : temperature, light... ? Which unfavorable environmental factors are ultimately involved?

 

[roy]

If you want a specific answer you should ask a specific question.

 

[kaysie]

I think that neoteny is kind of 'hit or miss'. Where some larvae in a pond may morph, others may not. Even from the same clutch!

I don't think it's a specific set of parameters, but more of a case-by-case instance where the larvae is able to stay in the water (as most larvae-ponds dry up), and conditions on land are not favorable (very hot, very dry, etc).

 

[rodrigo]

Read somewhere that water depth is an important factor...also cold temperatures...

 

[a.]

Thank you again, yet the subject still seems to remain shrouded within an enigma / mystery, tantalisingly illusive, yet beautiful!
Hey, I think I should write poems instead of keeping newts!

 

[jennifer]

Yes, I think that cold temperatures favor neoteny. And genetics is probably the strongest factor; some populations are more likely to produce neotenes.

 

[kristen]

I know with some Ambystoma sp. like tigrinum and talpoideum, individuals won't transform until water conditions are no longer beneficial. Like other people have said, some individuals from the same clutch may transform early and others may not transform for years. Also, with water temperatures, cool water tends to be more productive (ie. more food). I'm not sure though if this transfers to newts or not. Also, for reference, this is personal observations from Carolina Bays, so other breeding sites may be dramatically different.

 

[a.]

Anyone heard of the effect of the thyroid hormone on amphibian larvae?

 

[ryan]

Is that the one that causes the larvae to transform?

 

[mark]

The thyroid is a gland that produces hormones which induce changes during metamorphosis in amphibians. Forced neotenes e.g. mudpuppies, amphiumas have tissue that is insensitive to thyroid hormones hence why they never morph. In facultative neotenes e.g. some Ambystoma, Notophthalmus, Triturus etc it’s been shown that thyroid hormones induce metamorphosis. Evidence suggests that neotenic animals have some failure in hypothalamic activity which in turn controls thyroid activity – hence the lack of metamorphosis.

 

[ryan]

Oh alright thats what I thought so A. Luongo I have heard of this before.

 

[a.]

Cool, thanks very much for a clear thorough answer pin-pointing the underlying cuase.