T. vulgaris egg survival rate

[al]

My small colony of T. vulgaris has one (possibly two) gravid female starting to lay eggs.
I have several questions.
*It appears the females started showing sexual characteristics before the males; the males have enlarged cloaca, but no real large crest...is this possible? Can a female gravid with eggs lay unfertile eggs (no spermatophore transfer)with the same maticulous effort? I'm thinking the males need full crests to be ready for mating.
*I have noticed some leaf packets with eggs to be growing mold...are these the typical 50% that abort during tail formation...what is the typical time frame during miosis/egg development do these abortions occur?
*Has anyone allowed the offspring to remain in the tank with adults...with any success? I plan on removing some eggs to separate containers.
*How bad is predation on eggs by adults? My cynops p. did not ravage the eggs as bad as my Pleurodele walts...I had to remove eggs every 12-24 hours.
Sorry for all the questions...any information will be much apreciated.
Al

 

[john]

Hi Al. I'm not an expert on T. vulgaris, but I think I can offer some info.

The males of some subspecies of Triturus vulgaris don't have high crests, e.g. T. vulgaris meridionalis, so your males may well have completed their sperm cycle (have you seen yours in breeding dress before?). It is possible for most, if not all, species of salamander to lay infertile eggs, for whatever reason. I have seen axolotls mate, but since the male hadn't finished spermatogenesis there were no sperm caps on the spermatophores, and though the female laid eggs, they were infertile. If your males are still developing crests, I do think it's probable that they already have viable sperm.

Forgive my ignorance on the second point, but I thought that only some Triturus species (cristatus/marmoratus complex) had this 50% abortion problem? In any case, tail-bud formation only occurs after neurulation (the egg flattens on one side and then forms into a more larva-like shape). The tail then begins to jut out at one end after a day or two and I think development stops then in the problem 50%. It could take anywhere from a week to 3 weeks to reach that stage, depending on temperature - tailbud formation is about half way through embryo's development.

I've never heard of larvae surviving with adults. Generally they'd all be eaten. The only chance they'd have is if you have a large land area and the parents leave the water after mating/egg laying (generally the males of vulgaris stay in the water for months though - I've caught wild males in full breeding dress in mid-July). A lot of water weed would help too.

In leaf-wrapping species (as opposed to those that just lay their eggs on plants with no wrapping), egg predation is much reduced because the parents generally don't find the eggs. It may sound simplistic but well-fed adults tend to not eat many eggs anyway.

-John

 

[nimbus2]

Hi Al, congrats on your eggs. John is correct, only cristatus, dobrogicus, carnifex, karelinii, and marmoratus have the 50% mortality trait. Also, I've had a female T. boscai lay 12 infertile eggs with all the care of any mother laying fertile eggs. She laid the 12 infertile, then began laying fertile eggs.

Someone on kingsnake once posted about the fact that he had left all of his T. helveticus eggs and larvae in with the adults and they were not eaten. He was wondering if the stories of adults eating eggs and larvae were a myth. While it has been shown that parents often ignore their own offspring and are far more likely to eat clutches of eggs/larvae from other adults, I personally wouldn't take the chance.

 

[al]

Thanks for the input.
I recieved this small colony last spring, so this is my first season. Good point about subspecies and appearances, they may be meridionalis.

Now that you mention it, I remember that not all Triturus sp. have this genetic defect with abortions after neuralation development. They first few that are starting to mold, may in fact be unfertile. Man, these eggs are tiny, and dealing with a leaf packet makes it near impossible to verify fertility or development.
My Cynops pyrrhogaster layed very simular clutches. There were so many I just kept replacing the plants, transfering them to a nursery setup until they hatched out. Other sp. that lay openly on objects etc.; it is easier to monitor egg status and manipulate the environment (temp., aeration, water quality etc.)
Thanks for the input.
BTW Great site

 

[john]

Hi Al,

I thought you'd like to see these photos of Triturus vulgaris vulgaris males. It's only the start of the breeding season, so they're not quite in full breeding dress (the crests aren't fully grown), but I thought you'd like to see them anyway. Three of these photos are the same male, and one is different. I hope to take more photos when they have fully developed crests.

 

[al]

Thanks for the pics...
I think mine are not fully mature yet this season. The males are not doning the same dress.
Did you have a sig. temperature drop prior to this display? How long?
Thanks
Al

 

[john]

Hi Al.

These are wild newts - I caught them just for the sake of photography and released them the next day. They went through a normal English winter. Winter in this part of England is quite mild. For example, it hardly ever snows here. These newts were caught when there was a thin layer of ice on the water, believe it or not. It was a degree or two colder on that day though - it has generally been warmer, say 4 to 8 degrees C at night. Those newts are probably now in full breeding dress (photos were taken 2 weeks ago) because breeding season is fully underway, so I might catch a few again and take more photos if you like. The crest becomes higher and somewhat jagged.

All the best,

-John