High UVI index appears to slow growth of Furcifer lateralis (Carpet chameleon) juveniles

[javadi]

I raised some F. lateralis babies under UVI 3 and UVI 7, then weighed them at various timepoints. It would appear that under UVI 7, they grow slower or obtain lighter weights at 10 weeks. At week 8, the differences between the groups were not significant, but at other timepoints they were. It therefore seems disadvantageous to raise baby lateralis under high UVI. Lots of different explanations are possible, but one is that under higher UVI, they are likely to hide more, therefore not hunting, basking etc. so metabolism is slowed and they don't grow as fast. If you want to discuss, post your own interpretation of this data here! Of course there are limitations to this small study as is the case with any investigation worth doing.

 

[Beman]

Very interesting... I feel like a saw another study like this in another forum but it was on furcifer pardalis. Same type of results... higher UVI slower growth rate. I just went to search the other group and I can not find it now though.

 

[javadi]

This work has now been officially published, feel free to read the whole thing here:

https://www.dropbox.com/s/qzapweioi...4nk9xx7TefDGffpTk0uCoDrhM7fwWKkxby-XCUW_28kGI

 

[kinyonga]

Link won't open for me.

 

[javadi]

Link won't open for me.

 

[kinyonga]

Thankyou @javadi !! That worked!,

It said..."Overall, our study suggests that high levels of UV light do not increase juvenile F. lateralis growth rates, supporting the use of moderate levels of UV when raising F. lateralis, at this early stage in development"...any idea why the higher levels don't increase the growth rates? (Now I'm going to have to look into this to satisfy my curiosity you know! )

 

[javadi]

Thankyou @javadi !! That worked!,

It said..."Overall, our study suggests that high levels of UV light do not increase juvenile F. lateralis growth rates, supporting the use of moderate levels of UV when raising F. lateralis, at this early stage in development"...any idea why the higher levels don't increase the growth rates? (Now I'm going to have to look into this to satisfy my curiosity you know! )

Glad you gave it a read! The original version included some speculation about that question, but it was edited out for length reasons. To answer it (speculation) though....

One idea is that the high UV levels cause cellular damage, and as a result, resources (nutrients, macromolecules) that would typically be allocated towards growth and development were instead used for tissue repair. Thus, growth was limited.

Another possibility is that the animals exposed to higher UV levels spent more time hiding from the light, and therefore were not in the warmer, more exposed regions of the enclosure for as long. Therefore, they had "slower" metabolism and didn't grow as fast with high UV levels. More time spent hiding could also have, in theory, limited food intake to an extent and therefore slowed growth.

There's a couple other options too. Future work could assess chameleon behavior to see how the high-UV group spent their time and whether it was different than the lower UV group. As is, we can't attribute the findings to direct effects of UV or due to behavioral changes as a result of the high UV levels. Outside the scope of the study but someday perhaps it can be investigated!

 

[dinomom]

Glad you gave it a read! The original version included some speculation about that question, but it was edited out for length reasons. To answer it (speculation) though....

One idea is that the high UV levels cause cellular damage, and as a result, resources (nutrients, macromolecules) that would typically be allocated towards growth and development were instead used for tissue repair. Thus, growth was limited.

Another possibility is that the animals exposed to higher UV levels spent more time hiding from the light, and therefore were not in the warmer, more exposed regions of the enclosure for as long. Therefore, they had "slower" metabolism and didn't grow as fast with high UV levels. More time spent hiding could also have, in theory, limited food intake to an extent and therefore slowed growth.

There's a couple other options too. Future work could assess chameleon behavior to see how the high-UV group spent their time and whether it was different than the lower UV group. As is, we can't attribute the findings to direct effects of UV or due to behavioral changes as a result of the high UV levels. Outside the scope of the study but someday perhaps it can be investigated!

Very intriguing thanks for sharing!

 

[kinyonga]

You said..."Glad you gave it a read! The original version included some speculation about that question, but it was edited out for length reasons. To answer it (speculation) though."...how could I not read it!!??!!

You said..."One idea is that the high UV levels cause cellular damage, and as a result, resources (nutrients, macromolecules) that would typically be allocated towards growth and development were instead used for tissue repair. Thus, growth was limited"...this sounds possible to me..

You said..."Another possibility is that the animals exposed to higher UV levels spent more time hiding from the light, and therefore were not in the warmer, more exposed regions of the enclosure for as long. Therefore, they had "slower" metabolism and didn't grow as fast with high UV levels. More time spent hiding could also have, in theory, limited food intake to an extent and therefore slowed growth."...they might have spent more time hiding from the light but then wouldn't they have had less exposure to the higher UVB at the same time? Did they free range the food?

You said..."There's a couple other options too. Future work could assess chameleon behavior to see how the high-UV group spent their time and whether it was different than the lower UV group. As is, we can't attribute the findings to direct effects of UV or due to behavioral changes as a result of the high UV levels. Outside the scope of the study but someday perhaps it can be investigated!"...it's easy to not realize that you should look at other options as an experiment is going on. Sometimes it takes digestion of the events so you can wrap your mind around it...life you know what I mean.

 

[kinyonga]

You do realize that this is all going to keep me awake at night now, don't you?

 

[bbyoda]

Thank you for contributing to our knowledge base of chameleons!

 

[javadi]

You do realize that this is all going to keep me awake at night now, don't you?

Haha well my apologies! At least it's a good reason!

 

[javadi]

You said..."Glad you gave it a read! The original version included some speculation about that question, but it was edited out for length reasons. To answer it (speculation) though."...how could I not read it!!??!!

You said..."One idea is that the high UV levels cause cellular damage, and as a result, resources (nutrients, macromolecules) that would typically be allocated towards growth and development were instead used for tissue repair. Thus, growth was limited"...this sounds possible to me..

You said..."Another possibility is that the animals exposed to higher UV levels spent more time hiding from the light, and therefore were not in the warmer, more exposed regions of the enclosure for as long. Therefore, they had "slower" metabolism and didn't grow as fast with high UV levels. More time spent hiding could also have, in theory, limited food intake to an extent and therefore slowed growth."...they might have spent more time hiding from the light but then wouldn't they have had less exposure to the higher UVB at the same time? Did they free range the food?

You said..."There's a couple other options too. Future work could assess chameleon behavior to see how the high-UV group spent their time and whether it was different than the lower UV group. As is, we can't attribute the findings to direct effects of UV or due to behavioral changes as a result of the high UV levels. Outside the scope of the study but someday perhaps it can be investigated!"...it's easy to not realize that you should look at other options as an experiment is going on. Sometimes it takes digestion of the events so you can wrap your mind around it...life you know what I mean.

Well, perhaps I should have said "thank you for reading it"! Very exciting to share this with the community

If they did spend more time hiding, then yes, they could have had less exposure to the higher UVB levels. Food was free ranged but I find fruit flies spend more time in the light in my setups than in the darker leaf cover, where the juvenile lats would be hiding. Crickets less so though. However, the study was designed to assess whether higher vs. lower UVB levels had any impact on growth, rather than figuring out a mechanism for UV's impacts on growth. This way it was applicable to captive husbandry. So what I mean to say is that there are some very interesting avenues to take this and follow up studies to pursue, but the actual amount of UV exposure they got at the end of the day doesn't change that offering high UV has the effect of slowing growth. It would be super interesting to see whether shorter periods of higher UVB vs. longer periods of lower UVB reproduced similar findings as here! Maybe in the future...

Along the same vein, here is another great study showing that a couple of Madagascar chameleon species get very low levels of UV in the wild (average UVI=0.3). I think we might be overcorrecting with the UVB exposures we provide as a backlash against MBD. Perhaps over time we will learn that lower UV levels are actually beneficial for some species.
https://pubmed.ncbi.nlm.nih.gov/30474137/#:~:text=nasutum) in the field in,both species was only 0.3.

 

[jamest0o0]

These are the kind of threads that always keep me coming back to this site. I’ll be pondering this!

 

[kinyonga]

You said..."Well, perhaps I should have said "thank you for reading it"! Very exciting to share this with the community "... No need to thannk me ...I read everything I have time to read.

You said...If they did spend more time hiding, then yes, they could have had less exposure to the higher UVB levels. Food was free ranged but I find fruit flies spend more time in the light in my setups than in the darker leaf cover, where the juvenile lats would be hiding. Crickets less so though. However, the study was designed to assess whether higher vs. lower UVB levels had any impact on growth, rather than figuring out a mechanism for UV's impacts on growth. This way it was applicable to captive husbandry. So what I mean to say is that there are some very interesting avenues to take this and follow up studies to pursue, but the actual amount of UV exposure they got at the end of the day doesn't change that offering high UV has the effect of slowing growth. It would be super interesting to see whether shorter periods of higher UVB vs. longer periods of lower UVB reproduced similar findings as here! Maybe in the future"...I'm still interested in figuring out the mechanism for UV's impact on growth. There can be some interesting studies done playing with the UVB.

You said..."Along the same vein, here is another great study showing that a couple of Madagascar chameleon species get very low levels of UV in the wild (average UVI=0.3). I think we might be overcorrecting with the UVB exposures we provide as a backlash against MBD. Perhaps over time we will learn that lower UV levels are actually beneficial for some species."...we still have lots to learn...and I see you've provided another link.

https://pubmed.ncbi.nlm.nih.gov/30474137/#:~:text=nasutum) in the field in,both species was only 0.3.