# Sex Ratios in Dart Frog Off Spring



## Guest (Mar 8, 2004)

Has anyone tried experimenting with differnt water temps and air temps to see if this effects the sex ratios we are getting with the frogs we produce?
I know that Azureus run heavy female, imitator run heavy male, and orange basti pumilio run heavy male. 
I know most of this would have us raising the frogs up to adults. I am trying an experiment with letting an adult female Azureus sex froglet by watching how see react with them. So far I am guessing 1 male and 4 female froglets but have to wait as see if she is right.
So has anyone tried anything like this?


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## Guest (Mar 8, 2004)

interesting theory.... i know the sex of crocs and a few others sex are based on temp. Worth trying if someone has aurutus, vents or some other frogs that reproduce a lot.


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## Guest (Mar 8, 2004)

Ben,
As we have talked about before I am sexing froglets with my Costa Ricans the same way.I recently added a good sized froglet to my pairs tank and soon after watched my adult female wrestle it.I'm betting female. One down twenty to go, :lol: :lol: .Oh, and btw,I watched my male CR auratus deposit a tad into the catch pool.Spring is in the air :? 
Mark W.


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## Will (Feb 15, 2004)

So we have the beginnings of a basic working theory:

Histrionicus &Quinquevittatus - male at average frogroom temp.

Tinctorius - female at average frogroom temp.

Now what are peoples average frogroom temps?

Has anyone noticed opposite results with sex ration, and if so, what was the average frogroom temp?

Are we going to assume it’s a hot vs. cold sex determination or an extreme temps (hot/cold) vs. average temps?

I have incubators at work and could test some controlled extremes, but what temps would be considered safe extremes?


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## andersonii85 (Feb 8, 2004)

*Amphibians and sex determination*

Had to chime in here. 

Sex determination in amphibians follows either the XX-XY pattern; however, they are different than humans. From what I remember they use a signaling receptor for specific insulin receptor genes in order for testis formation. What this means is that it is not exactly the x or y chromosmes that determine the sex, but other genes on the chromosome that signal for it. Sort of a rudimentary "y". My guess is that females are determined by the abscence or inclusion of one of those receptors. 

Temperature does have an effect on these receptors and it has been shown in the laboratory. However, all they have shown is that if the temps are too high or low the embryo will develop, but will be sterile.

By the way, most species of amphibians in the wild are heavily male biased. Not only that, some geographic locations can be male biased while another population that is close can be female biased. Perhaps the frogs in the hobby have been collected from such areas and that could contribute to the bias's we are seeing. Many have conjectured why this is, but most agree that this does not apply to lab reared individuals because unusual sex ratios may be observed. This may be true for the hobbyists collection also. 

Justin (Biology major- just so you know)


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## kyle1745 (Feb 15, 2004)

*Re: Amphibians and sex determination*

Very interesting...



andersonii85 said:


> Had to chime in here.
> 
> Sex determination in amphibians follows either the XX-XY pattern; however, they are different than humans. From what I remember they use a signaling receptor for specific insulin receptor genes in order for testis formation. What this means is that it is not exactly the x or y chromosmes that determine the sex, but other genes on the chromosome that signal for it. Sort of a rudimentary "y". My guess is that females are determined by the abscence or inclusion of one of those receptors.
> 
> ...


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## Guest (Mar 10, 2004)

*Re: Amphibians and sex determination*



andersonii85 said:


> Had to chime in here.
> By the way, most species of amphibians in the wild are heavily male biased. Not only that, some geographic locations can be male biased while another population that is close can be female biased. Perhaps the frogs in the hobby have been collected from such areas and that could contribute to the bias's we are seeing. Many have conjectured why this is, but most agree that this does not apply to lab reared individuals because unusual sex ratios may be observed. This may be true for the hobbyists collection also.
> Justin (Biology major- just so you know)


Thanks Justin! Now time to pick your brain some more  What are some of the theories of what is the causation? If you have a few refrences you could point me to I would love to read them. I guess what I am really looking at is if you keep say 2 male imitator and 1 female will she be more likely to produce girls? But if their are wild populations that are bias then that shoots a big whole in the chances. 
My last biology class was over 9 years ago, but I am going back in the fall to refresh and possible start down the road on a biology degree.

Thanks again for the information,


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## andersonii85 (Feb 8, 2004)

*Re: Amphibians and sex determination*

Thanks Justin! Now time to pick your brain some more  What are some of the theories of what is the causation? If you have a few refrences you could point me to I would love to read them. I guess what I am really looking at is if you keep say 2 male imitator and 1 female will she be more likely to produce girls? But if their are wild populations that are bias then that shoots a big whole in the chances. 
My last biology class was over 9 years ago, but I am going back in the fall to refresh and possible start down the road on a biology degree.

Thanks again for the information,[/quote]

Hey not a problem. As of now there isn't much data that points to anything definate, but there are some interesting ideas floating about. Here are some interesting articles:

Hayes, TB. Sex determination and primary sex differentiation in amphibians: Genetic and developmental mechanisms. Journal of Experimental Zoology [J. Exp. Zool.]. Vol. 281, no. 5, pp. 373-399. 1 Aug 1998.

Cevdet Uguz, Mesude Iscan and Inci Togan. Developmental genetics and physiology of sex differentiation in vertabrates, Environmental Toxicology and Pharmacology, Volume 14, Issues 1-2, June 2003, Pages 9-16 

These are pretty hard to get if you don't gave access to a collegiate library- I could attach them to an email if you would like. 

I have some ideas myself in that males may be more abundant in anuran populations due to the fact that females are the ones who make the mate choices; as a result, it may be advantageous for them to be able to choose from a whole multitude of males. I often get frustrated when breeding some tree frogs because I will keep a few from a batch and find out that they are all males. In Red eye tree frogs alone the average is roughly 1 female for every 25-40 males (depends on who you talk to). 

You should look into getting your bio degree- the pay isn't very good for research positions, but it is a heck of a lot of fun!

Justin[/quote]


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