Incubation Experiment LONG POST
Hello all I am required to do a senior research project to graduate. I chose to do my research on my favorite subject Ball pythons. :) It is an interesting project and I thought I would share my findings for anyone in the industry who would like the info.
My findings were presented to the Stetson University Biology Department Faculty, Juniors and Seniors. If anyone is interested in the complete paper feel free to email me and as soon as I have completed it I can send it to you. I am hoping either myself or my professor adviser will present the findings at the World Congress of Herpetology in Aug. 2012.
The following is a brief description of my project:
We all know that incubation temperature is important for egg laying species of reptiles. There is much debate on which temperature is best to incubate ball python eggs at. In my research I found that ball python eggs in the wild incubate at an average temperature of 30 degrees C. These studies where based out of togo. I wanted to see if there was any statistically significant difference between this "natural" incubation temp and those used in captivity.
For my experiment I used the clutches of 11 females bred here at Kelly's Balls. I also used a split clutch design to help control for the genetic and maternal effects on the eggs/hatchlings. As each clutch was laid I separated the eggs (the best I could). Each half was placed in identical Iris 6qrt tubs with 280g of dry vermiculite and 346g water. Then 1 tub was placed in an incubator set to 30C (86F) while the other was placed in an incubator set to 33C (91F). The eggs where monitored through out incubation.
Incubation time was measured as the time from the day the clutch was laid to the the time the first egg pipped. Once the first egg pipped I made a 1 inch slit in the rest of the eggs of that clutch in that treatment and monitored emergence time.
Emergence time was measured from date of first pip until when an individual completely emerged from their egg.
Over the 1st 30 days of life I recorded sex ratio, weight in grams, snout-vent length (SVL), growth rate and appetite.
growth rate was defined as grams/day and calculated by (weight on day 30-weight on day 1)/30
Appetite was defined as whether or not a hatchling ate at all during the first 30 days of life.
Based on the findings the only dependent variable in which incubation temperature had a statistically significant main effect was incubation time. Eggs incubated at 33C (91F) had a mean hatch time of ~59 days.
Eggs incubated at 30C (86F) had a mean hatch time of ~66 days.
There was no statistically significant difference in the sex ratio or appetite of the hatchlings.
There was a no statistically significant main effect of incubation temp. on SVL, weight or growth rate. There was a statistically significant effect of clutch on SVL, weight and growth rate as well as a clutch x treatment interaction effect.
There was a statistically significant main effect of incubation temperature on mean emergence time as well as a statistically significant effect of clutch and a statistically significant clutch x treatment interaction effect.
There is more data that I have not yet analyzed like head width, head length and interocular distances of the hatchlings. As well as their date of first shed and feed, latency to strike and time to subdue. However with the results from the data analysis that has been done I may not go back and do this analysis unless I repeat the experiment.
Yes there are a few problems with the experiment.
1. Small sample size.
*We were forced to move in the middle of breeding season and ~ half
of the females bred reabsorbed or did not lay.
*We lost power at the end of the experiment while 3 clutches were still
in he incubator and while they still hatched fine it was a temperature
dependent experiment and we could not include those clutches.
* I did not include the clutches of any female that was "loaned out" and
bred at a different location.
2. Unable to determine individual egg size at laying. Not all of the clutches where able to be completely separated and I was unable to weigh each egg individually.
3. None of the genetics of the sires or dams where taken into account.
In the end I feel it is a good start for some real data on artificial incubation at different temps in captivity. And there appears to be no negative effect on the hatchlings to incubate them at higher temps. They are no smaller than their low incubation temp counterparts and their is no difference in the sex ratio, appetite or growth rates.
I know this was long but I hope it will be helpful.
Thanks
Kelly Pyle
kellysballs@me.com
