faster metamorphosis in Triturus cristatus

France, British isles

faster metamorphosis in Triturus cristatus

Postby Will Atkins » Mon Jul 27, 2020 1:27 pm

In the UK crested newts are protected as a rare and declining species. One problem they have is slower metamorphosis times which means they need more permanent ponds for breeding than smaller newt species. However they cannot tolerate fish which are often present in more permanent ponds - 'catch 22'.

At two sites that I monitor I have found smaller than usual GCN metamorphs - c4cm rather than 6-7cm. They have the dark skin and gill stubs of metamorphs and they walk, rather than wriggle (all characteristic of metamorphs rather than larvae) earlier than usual - mid July rather than mid August - early September which was traditional for metamorphosis time in southern England 20 or 30 years ago. The ponds have dried up, so any remaining larvae would be killed.

Now for the question: I wonder if this rapid metamorphosis is due to:

1 - warmer water allowing faster development

2 - natural selection for individuals with faster metamorphosis (and their offspring)

3 - phenotypic plasticity - ie larvae 'choose' to metamorphose earlier as they detect falling water levels and imminent death.

Does anyone have any thoughts or literature they know of that could help with this? Thanks in advance!
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Re: faster metamorphosis in Triturus cristatus

Postby Michal Szkudlarek » Sun Aug 02, 2020 7:28 am

Maybe all of these 3 things play a role?
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Re: faster metamorphosis in Triturus cristatus

Postby Will Atkins » Sun Aug 09, 2020 3:32 pm

I'm sure you are right, I'd love to know if all 3 are equally important... Here's a link to a photo taken today of another site where the water often evaporates before metamorphosis is possible, but this year it looks like they were lucky!

https://www.flickr.com/photos/100121190 ... en-public/
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