Excess females from M. alpestris apuanus?

[alan]

Survival rate among my eggs/larvae is pretty good, better than 50% at least.

 

[mark]

Hmm… In the link Jen provided about Triturus it says 18-24 degrees Celsius produced a 1:1 ratio and cooler temps produced excessive females. I wonder what their cooler temperatures were? I’m fairly certain in the wild many crested newts will breed at much cooler temps than 18C. We don’t see excessive females in the wild so this is strange. What’s clear is that genetics is not the only mechanism that determines sex but environmental factors can play a role (both ZZ/ZW and XX/XY). Water chemistry, lighting, food, temperature etc. Any of them might be responsible for unbalancing the estrogen levels in larvae. Someone needs to get experimenting

 

[edward]

It turns out that there is a genetic component to TSD resulting in variation in how the sex ratio is expressed at given temperatures. There is a recent article in Herpetologica (I can get the reference later).

If I remember correctly with respect to the Pleurodeles, it isn't a true TSD as the supposed males are still genetically female. The high temps change the expression of the gene but don't truley determine the sex.

Ed

 

[joseph]

Ed: Are these males able to function normally?(reproduce)

(Message edited by fishkeeper on August 17, 2006)

 

[michael]

You guys had me scared. I thought I wasn't going to find any males. Out of the ones I am raising from eggs I found a nice young male yesterday. They are just barely big enough to sex but I think his bulge is a sure thing. I have not sexed enough to figure out ratios. I think males tend to show obvious sexual characteristics before females. Their is a possibility we are dealing with to small of a sample to determine anything.

Their have been hints of raising of larvae determining sex ratios in dart frogs. I think in the long run most of those guesses don't prove out.

 

[charles]

I just saw a male doing some tail fanning to a female, they were face to face for about 3 min., some of them are a little over 3 in. and still have gills, why? I hope they breed next year.

 

[jennifer]

When you say "next year", Charles, do you mean spring of 2007? Because it sure sounds like they might breed this coming season. However, sometimes the males are ready sooner than the females. Alpestris can grow up very fast.

 

[charles]

I hope my apuanus don't breed that soon, I was thinking that it would be spring of 2007. The one's that were doing this were right at 3in. and still have gill's, they look like they have a fro, they can't breed that soon can they?

 

[jennifer]

If they are tail-fanning, and they have the "fro", then they are sexually mature males (the gills don't matter). Whether the females are ready or not is another question.

 

[charles]

Some of my apuanus still have gill's and they are 4in. why?

 

[charles]

Update, my first egg hatched 2 day's ago, and I have a clump of java moss full of egg's I need to get out.

I can't belive that they breed so soon, it seems like I just took down the brine shrimp hatchery and now I need to get it going again.