Raising temps on females

[SteveB]

What type of developmental change would you see as beneficial? The only changes I have seen from any type of temperature changes, be it gradual, spikes or just fluctuations, have been detrimental.

I share your negative experiences, which is why the first half of my post was dedicated to stating that I felt stable temperatures should be used.

The second half of my post was highly theoretical, something that could only truly be tested in lab conditions.

We know temperature determines sex. We know temperature results in a sometimes significant alteration of pigmentation. We also have stories of "hot" females which are physically identifiable as females but express an aggressive demeanor and are poor breeders.
We know temperature fluctuations can result in deformities, we know that temperature fluctuations can result in anything from halting of eyelid development to kink tails, etc.

What if there is a certain temperature where internal organs develop better? What if there is a certain temperature where muscle tone improves? or bone density?
And so on...

Leopard geckos have evolved to physically develop differently depending on incubation temperature. That is a fact. What we don't know is the full extent of which the influence of temperature truly affects development.

 

[Golden Gate Geckos]

We also have stories of "hot" females which are physically identifiable as females but express an aggressive demeanor and are poor breeders.

Early studies suggested that females that were produced from higher incubation temperatures had 'altered' endocrinological characteristics and were more aggressive than females incubated at lower temps, and it was believed that they were sterile. Thus the term "hot females". Later studies proved otherwise, and no hormonal differences were noted. What they did find was, that these females reached reproductive maturity much later than females incubated at lower temperatures.

 

[SteveB]

Do you have those studies? If there was no hormonal difference noted, then what was the explination for the maturity rate? Were the later studies consistent with the early studies and how did they account for the different findings?

Personally I only ever worked with one hot female, and she certainly was both aggressive to other leos and a poor breeder even past year 2.

 

[Golden Gate Geckos]

Do you have those studies? If there was no hormonal difference noted, then what was the explination for the maturity rate? Were the later studies consistent with the early studies and how did they account for the different findings?

No, but I wish I did! I know that Dr. Brian Viets did a study in 1993, and then A. Tousignant did another study in 1995 that was published called "Otogenic and social factors affecting endocinology and timing of reproduction in female leopard geckos, Eublepharis macularius, Hormones and Behavior 29:141-153". I'm not sure how or where to obtain a copy of that report.

 

[Golden Gate Geckos]

OK, I Googled it, and found the abstract for the article.

 

[MHGeckos]

So the so called "hot females" are not sterile but reach reproductive maturity later than females incubated in constant temperature?

 

[Golden Gate Geckos]

So the so called "hot females" are not sterile but reach reproductive maturity later than females incubated in constant temperature?

From my understanding in this study, the females that came from higher incubation temperatures did not ovulate until about a year or more later than females incubated at lower temperatures. The earlier study thought those females were sterile.

 

[MHGeckos]

From my understanding in this study, the females that came from higher incubation temperatures did not ovulate until about a year or more later than females incubated at lower temperatures. The earlier study thought those females were sterile.

I think the same way...
I have 3 Sunglow females form 2006 that did not ovulate. I know that they could be incubated in high temperatures (I did not hatch them). They are about 20 months old. I hope they will ovulate this coming year.

 

[SteveB]

From my understanding in this study, the females that came from higher incubation temperatures did not ovulate until about a year or more later than females incubated at lower temperatures. The earlier study thought those females were sterile.

Somewhat of an odd study, but it seems to clearly support my theory..

From the abstract-

Overall, these data show that hormone levels and behavior change coordinately during the reproductive cycle. Although incubation temperature has persistent effects on endocrine physiology in adult female leopard geckos, these effects are modest compared to hormonal changes across the reproductive cycle.

I would say the physiological effects of incubation temperature is significant if it can cut in half the rate of maturity.
Perhaps the change in relative hormonal values is modest in comparison to the variation throughout the reproductive cycle, but it obviously is enough to alter the development of females.

The article also does link behavior to the reproductive cycle, which would explain the behavior seen in hot females.

 

[SteveB]

Here's a related abstract that is based on more recent research
http://www.sciencedirect.com/scienc...serid=10&md5=754e901713a78943cab489ffa68b5732

In females, age and incubation temperature affected E2 and dihydrotestosterone (DHT) but not T concentrations. Controlling for age, females from 34 °C have higher DHT and lower E2 levels than females from 30 °C. Further, E2 concentrations increased significantly from 2 to 10 weeks, after which E2 levels remained steady. Together, these results indicate that sexually dimorphic levels of steroids play a major role in the development of leopard gecko behavior and morphology. Furthermore, these data suggest that the organizational effects of incubation temperature on adult female phenotype could be, in part, mediated by incubation temperature effects on steroid hormone levels during juvenile development.

 

[Golden Gate Geckos]

Interesting indeed!

 

[SteveB]

Of course, neither document addresses temperature variations over the course of incubation, just the effect of various stable temperatures on gender and reproductive specific hormones and behavior. However I believe it supports my theory that it may be possible to further engineer the development of leopard geckos by altering incubation temperature. Certainly the data should give us reason to consider what stable temperature we choose to incubate at.

 

[Golden Gate Geckos]

I'm being somewhat sarcastic here, but what is to stop someone (maybe you, Steve? ) from going to weather.com and tracking the temperature fluctuations in the mountainous deserts of Pakistan from day to night over a period of the months of July and August, and setting up an incubator to parallel those gradual temprature fluctuations? That would be the BEST way to support the theories associated with temperature vs. gender, temperature vs. color, and temperature vs. endocrinology of leopard geckos.

It looks like there haven't been any more studies on this for about 10 years!

 

[Baysidegeckos]

From my understanding in this study, the females that came from higher incubation temperatures did not ovulate until about a year or more later than females incubated at lower temperatures. The earlier study thought those females were sterile.

My females are at 83F for 1 month and at 90F for the next 2 weeks and then hatch, and my females that i held back for example: she was born 4/20/07 and is currently 65 grams and is already laid 1 clutch that was 2 eggs, and she was only 7 months old when she started ovulating for the first time. Another female is born 4/21/07 is currently 64 grams and is ovulating at the moment. So they are ovulating around the same time as alot of the other females i have seen others produce at a steady 80-83 degrees temps.

 

[SteveB]

Well Marcia, you'd also have to account for where the eggs are actually laid and what type of temperature fluctuation is experienced in that location compared to reported temperature in the region. :main_robin:

 

[Golden Gate Geckos]

Well Marcia, you'd also have to account for where the eggs are actually laid and what type of temperature fluctuation is experienced in that location compared to reported temperature in the region. :main_robin:

Well Steve, it sounds like a road trip to Pakistan is in order!

 

[SteveB]

Well Steve, it sounds like a road trip to Pakistan is in order!

You buying the tickets?

 

[Stitch]

Here's a little something to chew on. I bought 2 female geckos (from different parents), one was a line bred snow and the other a tremper albino. These gecko's hatched 2 weeks apart. My snow wound up ovulating at about 10 months old and around 48 grams. It took my albino another whole year before she started ovulating for the first time. So she was about 2 when she started laying.

P.S. The tremper albino female with bright male colors is the most personable and kindest gecko that I have.

 

[yellermelon]

ROADTRIP, lets roll.
next stop Pakistan

 

[paulnj]

My cousin just went to that region with the marines:main_lipsrsealed: He followed in dad's footsteps and carries a Barrett 82A1 50BMG :main_yes: Osama hunter, maybe he can grab a gecko for me.