Tongues of three species of chameleon...
- Thread starter kinyonga
- Start date
Chris Anderson
Dr. House of Chameleons
Ugh, this is one of those studies that should have never made it through peer review. Having studied the chameleon tongue for my dissertation, I was shocked to see this published. There are a ton of issues with the authors using completely incorrect terminology for the tongue and hyoid apparatus in chameleons, but more importantly looking at the methods and results there is also very evident issues with their identification of the species used in this study. In particular, Chamaeleo vulgaris is a synonym of Chamaeleo chamaeleon, so they only actually looked at 2 species (C. africanus and C. chamaeleon). Unfortunately, they also claim to have collected the C. vulgaris in "Sidi-barani, south of Egypt". The problem is, Sidi-barani (at least the only one I have been able to find) is on the northwest coast of Egypt (where C. chamaeleon does occur), but C. chamaeleon does not occur in the south of Egypt. So, either they have identified their specimens incorrectly (if the specimens were in fact collected in the south of Egypt), or all the differences they note between C. chamaeleon and C. vulgaris specimens (which is where most of the difference they note are observed) are just individual variation and not indicative of species level difference as they claim.
Chris
Chris
Chris Anderson
Dr. House of Chameleons
Absolutely, and its nice that you do! It can be difficult to critically analyze studies though if you aren't a specialist, so when I see one that I don't think is a good study, I try to chime in so others can see some of those issues with it.
Chris
Chris Anderson
Dr. House of Chameleons
If we are talking about the Sidi-Barani on the northwest Mediterranean coast of Egypt, that would be Chamaeleo chamaeleon. If there is another Sidi-Barani in south Egypt, that would have to be C. africanus. So either way they only would have compared two species and many of the differences they found are not actually species differences but individual variation.
Chris
Chris Anderson
Dr. House of Chameleons
Yep, except in the Nile delta you also find C. africanus coming north with the Nile to the coast, which is why you can also find them in Cairo. They seem to be restricted to that area, however in the northern part of the country.
Chris
Chris Anderson
Dr. House of Chameleons
Not sure, but I would guess so. The author of that study has published other SEM studies on Chamaeleo chamaeleon skin, for instance, so it is possible some of the same specimens were saved and used for these and other studies. In my lab I save the remaining tissue of specimens I use for studies so that I can use them in the future for other work, and that is fairly typical in many cases, particularly for specimens that are more difficult to get than just ordering them from a Biological Supply company.
Chris
So we're the other studies better than the tongue one in your opinion?
Chris Anderson
Dr. House of Chameleons
They suffered from some of the same issues regarding a lack of appropriate background on what has already been done on the topic (part of why they failed to use appropriate terminology in the tongue paper), but they at least focused on comparing different age groups of the same species, so they didn't have the issue with their results not actually representing what they thought they were looking at. So, I'd say they are better, but still not as high of quality as I would have hoped or as they could have been with a little effort to review the literature.
Chris
Now I'm curious...so I looked up more of their studies...
In this one they say..."The authors concluded that there is integration between corneal, retinal and Harderian gland functions to ensure good vision highly adapted for chameleon predation"... To ensure good VISION?? Harderian gland?...what am I not getting @Chris Anderson ?...
https://www.researchgate.net/public..._Harderian_glands_in_young_Chameleo_chameleon
In this one they say..."The authors concluded that there is integration between corneal, retinal and Harderian gland functions to ensure good vision highly adapted for chameleon predation"... To ensure good VISION?? Harderian gland?...what am I not getting @Chris Anderson ?...
https://www.researchgate.net/public..._Harderian_glands_in_young_Chameleo_chameleon
Never mind @Chris Anderson ....I found the whole paper...
"This involved in the stimulation of the acini to produce its mucous secretion for cleaning and sterilizing the eye"...never thought this would be the connection!
https://ijarbs.com/pdfcopy/mar2016/ijarbs9.pdf
"This involved in the stimulation of the acini to produce its mucous secretion for cleaning and sterilizing the eye"...never thought this would be the connection!
https://ijarbs.com/pdfcopy/mar2016/ijarbs9.pdf
Chris Anderson
Dr. House of Chameleons
Yep, quite probably all of the above. There are also inherent issues with equitable access to scientific literature that disproportionately impacts researchers outside North America, Australia and Europe, but in this case most of the background articles (particularly on the tongue) are available free online now, so that isn't the issue here. Regarding the peer review failing, this happens more with these fringe journals that these particular authors tend to target. Definitely frustrating.
Chris
