Axolotls escaping neoteny

[the tree]

Having had this really odd concept brought to my attention via this comic, and trying to learn more from this Wiki' article, I don't understand, how do Axolotls metamorphose? If it's not something they do regularly then how does the mechanism get unlocked on demand?

[CDarwin]

I'll leave the mechanics to Lucaspa and the like... It has to do with the quality of the water. Axolotls retain larval features and remain aquatic if they can.

[Royston]

Funnily enough I used to own an axolotl called 'Henry', *her diet was mainly chicken heart, and they have the strange behaviour of eating each other, through competition...chunks from a leg et.c.

 

I have no idea of the mechanics behind the regrowth of limbs, but axolotls have caused much activity in the study of stem cells.

 

*My axolotl was female, but I was eight and wanted a male

[CDarwin]

Funnily enough I used to own an axolotl called 'Henry', *her diet was mainly chicken heart, and they have the strange behaviour of eating each other, through competition...chunks from a leg et.c.

 

I have no idea of the mechanics behind the regrowth of limbs, but axolotls have caused much activity in the study of stem cells.

 

*My axolotl was female, but I was eight and wanted a male

 

I don't think that's what he's talking about.

[Royston]

I don't think that's what he's talking about.

 

I was procrastinating...but the axolotl AFAIK isn't in larvae stage, like a larval tiger salamander, which are. They do metamorphose to a salamander if there are dry conditions.

[Paralith]

I'll leave the mechanics to Lucaspa and the like... It has to do with the quality of the water. Axolotls retain larval features and remain aquatic if they can.

 

The basics are that sometimes signals external to cells can trigger a pathway that will utlimately express certain genes that otherwise remain unexpressed. And if never exposed to those signals, the genes will never be expressed.

[lucaspa]

Having had this really odd concept brought to my attention via this comic, and trying to learn more from this Wiki' article, I don't understand, how do Axolotls metamorphose? If it's not something they do regularly then how does the mechanism get unlocked on demand?

 

Part of the answer was in the Wiki article:

"Many species within the Axolotl's genus are either entirely neotenic or have neotenic populations. In the axolotl, metamorphic failure is caused by a lack of thyroid stimulating hormone, which is used to induce the thyroid to produce thyroxine in transforming salamanders."

 

If you want more details:

 

http://www.ijdb.ehu.es/web/contents.php?vol=40&issue=4&doi=8877439

J. Huxley. 1920. Metamorphosis of axolotl caused by thyroid feeding Nature 104: 436.

 

http://bio.research.ucsc.edu/~barrylab/classes/evolution/DEVO_EVO.HTM

"Some salamanders remain in the larval form and this is due to an inactivation of the thyroxine cascade. Different species of salamaders have thyroxine mediated metamorphosis interrupted at various points in the cascade.

In the axolotl, a neotenic salamander that breeds as an adult, you can simply feed it tissue with lots of throxine and it will transform to a terrestrial form."