Cyclic Colour Change in the Bearded Dragon P.vitticeps

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Cyclic Colour Change in the Bearded Dragon P.vitticeps

Postby kingofnobbys » Sun Aug 04, 2019 12:54 am

Scientific study topic :
Cyclic Colour Change in the Bearded Dragon Pogona vitticeps under Different Photoperiods
Marie Fan, Devi Stuart-Fox, and Viviana Cadena
PLoS One. 2014; 9(10): e111504.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4213017/

Abstract

The ability to change colour rapidly is widespread among ectotherms and has various functions including camouflage, communication and thermoregulation.
The process of colour change can occur as an aperiodic event or be rhythmic, induced by cyclic environmental factors or regulated by internal oscillators. Despite the importance of colour change in reptile ecology, few studies have investigated the occurrence of a circadian rhythm in lizard pigmentation.
Additionally, although colour change also entails changes in near-infrared reflectance, which may affect thermoregulation, little research has examined this part of the spectrum.

We tested whether the bearded dragon lizard, Pogona vitticeps, displays an endogenous circadian rhythm in pigmentation changes that could be entrained by light/dark (LD) cycles and how light affected the relative change in reflectance in both ultraviolet-visible and near-infrared spectra. We subjected 11 lizards to four photoperiodic regimens: LD 12∶12; LD 6∶18; LD 18∶6 and DD; and measured their dorsal skin reflectance at 3-hour intervals for 72 hours after a habituation period. A proportion of lizards displayed a significant rhythm under constant darkness, with maximum reflectance occurring in the subjective night.

This endogenous rhythm synchronised to the different artificial LD cycles, with maximum reflectance occurring during dark phases, but did not vary in amplitude. In addition, the total ultraviolet-visible reflectance in relation to the total near-infrared reflectance was significantly higher during dark phases than during light phases.

We conclude that P. vitticeps exhibits a circadian pigmentation rhythm of constant amplitude, regulated by internal oscillators and that can be entrained by light/dark cycles.

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ref Statistical Analysis of Biological Rhythm Data. Dowse HB (2007) Rosato E, editor.
Circadian Rhythms. Humana Press. 29–45.
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : , Fluffy (F) rescued injured by lawnwacker 14Nov17, Gutzy (F) rescued 27Sep19 - RIP 3Aug20 (est 12 yo), Wriggles (F) - injured rescue, over 8 yrs old, RIP 2Feb16 old age. Lucky juvenile (M) - cat attack rescue (lost r-eye, broken r-lower jaw), fatal SI RIP 21Jul2010.
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Re: Cyclic Colour Change in the Bearded Dragon P.vitticeps

Postby CooperDragon » Mon Aug 05, 2019 12:00 pm

That's a pretty interesting study. I'd like to know if they have similar findings with the larger study they are planning to do. I didn't realize that their skin reflectance is controlled as a circadian rhythm. According to the results it does look like their skin reflectance is affected by visible light wavelengths.
P. vitticeps seems to have one or more internal oscillators inducing a circadian pigmentation rhythm of constant amplitude that can be entrained by light/dark cycles and responds to light by a decrease in skin reflectance, this decrease being proportionately larger in the UV-Vis range than in the NIR range.


This makes me wonder (as they questioned in the article) if a sudden light cycle change affects them differently than a gradual one. I'm also curious about the effects/benefits of providing IR to keep them warmer overnight.
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Re: Cyclic Colour Change in the Bearded Dragon P.vitticeps

Postby kingofnobbys » Mon Aug 05, 2019 6:04 pm

CooperDragon wrote:That's a pretty interesting study. I'd like to know if they have similar findings with the larger study they are planning to do. I didn't realize that their skin reflectance is controlled as a circadian rhythm. According to the results it does look like their skin reflectance is affected by visible light wavelengths.
P. vitticeps seems to have one or more internal oscillators inducing a circadian pigmentation rhythm of constant amplitude that can be entrained by light/dark cycles and responds to light by a decrease in skin reflectance, this decrease being proportionately larger in the UV-Vis range than in the NIR range.


This makes me wonder (as they questioned in the article) if a sudden light cycle change affects them differently than a gradual one. I'm also curious about the effects/benefits of providing IR to keep them warmer overnight.


I've been sitting on this study for a while as I found it illuminating and that it ties in nicely with my own personal observations of my pets and of wild dragons and helps explain why bright overhead lighting is needed in our vivs for healthy dragons and why in the wild dragons orientate with their back facing the sun ( they can detect the polarization of the light from the sun ).
CBDs: Cleopatra & Caesar born 28Jan19.
Puff (RIP 10Dec15),Rex (RIP 16Mar17),Toothless (RIP 26Nov17).Peppa (RIP 22Mar19).
EBTSs : George & Mildred (born july 2010).
EWSs : , Fluffy (F) rescued injured by lawnwacker 14Nov17, Gutzy (F) rescued 27Sep19 - RIP 3Aug20 (est 12 yo), Wriggles (F) - injured rescue, over 8 yrs old, RIP 2Feb16 old age. Lucky juvenile (M) - cat attack rescue (lost r-eye, broken r-lower jaw), fatal SI RIP 21Jul2010.
kingofnobbys
BD.org Sicko
 
Posts: 12572
Joined: Tue May 12, 2015 10:56 pm
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