My little brother just adopted a juvenile bearded dragon and I thought it would be interesting to learn more about them. I read the article “Thermoregulatory behavior and orientation preference in bearded dragons.” As learned in class, lizards will use various types of behavior to thermoregulate, including various types of orientation. This study looked at thermal orientation behavior of Pogona vitticeps (bearded dragons) in adults and neonatal. Previous experiments have suggested that learning may be a part in behavioral thermoregulation, though overall it is thought to be innate and learned response. They discussed body orientation as orientation preference and wanted to discover if it is bias and better understand the innateness. They hypothesized that “orientation would present as a thermoregulatory mechanism in bearded dragons.” It was predicted that “bearded dragons would display non-random orientation behavior in a thermal gradient, choosing to face towards a heat source rather than towards a cold source.” Lastly, they also hypothesized that “preference for orienting towards a heat source would be conserved across multiple life stages, which would support an innate hypothesis for orientation behavior.” (Black, 172)
All the bearded dragons they used were captive bread. Seventeen were adults and twenty-six were neonates. During the experiment, thermal and orientation preference were measured using video recording and temperature sensing. An image was shot every30 seconds for six to eight hours. Orientation was facing heat or facing away from heat and movement was moving or stationary.
After the trials, they described that adult bearded dragons oriented toward the heat when at cool temperatures and as selected temperatures were reached, orientation became random. Also, lizards that were stationary often faced towards the heat. When the neonatal were first placed into the trial containers, selected temperature was not subjective to orientation, though during the end of the experiment, “selected temperature was increased when neonates were facing the cold, compared to when facing toward the warmth.” (Black, 175)
It was concluded from their results that adults orientate as a behavior related to thermoregulation, which is what we discussed in class. Also, that the behavioral orientation is more innate than learned in the neonatal. One of the last main points was that “orientation as a thermoregulatory behavior in neonatal bearded dragons, while present, does not appear to be as precise or as impactful on selected temperature as it does in adults.” (Black, 176) The bigger they are, they more precise they have to be in regulating their temperature.
Written by: Ian R.G. Black, Glenn J. Tattersall.
2 comments:
Did the authors suggest any possible reasons the dragons faced different directions depending on the thermal environment?
This is a very interesting article. Bearded dragons are one of my favorite herps, so it's always cool to hear new research about them. We've talked a lot about thermoregulation in lecture, so it's cool to learn that it's an innate behavior and not something that juvenile's learn. It always fascinates me to see how naturally adapted organisms are.
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