JUL 07, 2016 11:18 AM PDT

Not All Iguanas Are Herbivores, But Why?

WRITTEN BY: Anthony Bouchard

Lots of reptiles love their protein. They have a constant desire for the stuff to compliment their lifestyles, and that’s why there are so few herbivorous lizards out there.
On the other hand, iguanas seem to be capable of living off of a green-only diet, which is something that most reptiles prefer to avoid. So why is this the case?

Lizards may choose theri dietary path based on lifestyle.

Published in the Journal of Experimental Biology, researchers from Vanderbilt University share their findings of how various specimens of the Ruibal’s Tree Iguana collected from Argentina reacted to various diet types.
The researchers gave some of the specimens a vegetarian diet that was mildly supplemented with mealworm protein, and other specimens received a 50/50 hybrid diet of vegetables and mealworms.
After some time of feasting, the researchers then studied the reptiles’ bodies to learn more about how their bodily systems differed after the fact.
Among the things that were studied over a 40-day testing period were the iguanas’ body mass and feces. In the iguanas that ate the mostly vegetarian diet, they found the following intriguing details:

  • No change in body mass between the iguanas with differing diets
  • Less protein waste existed in the fecal samples of iguanas with vegetarian diets
  • Vegetarian iguanas had 20% longer small intestines than ones that ate a mixed diet
  • More plant-fermenting bacteria existed in the intestines of vegetarian iguanas

What can be concluded from this data is that iguanas are not limited by their bodies in what they can or cannot eat. Instead, depending on the species, it could be a personal preference and their bodies can adapt either way they choose to go.
So since this is the case, why don’t more reptile species munch on greens instead of protein?
The researchers have this theory: “We hypothesize that ecological contexts and the likely fitness benefits of feeding on energy-dense insects may be more critical in constraining the evolution of herbivory in liolaemid lizards,” said Kevin Kohl, lead researcher in the study.
It would seem that there are just more benefits to having more protein in a diet than not, and lizards have adapted through evolution to have more protein-rich diets over high-fiber ones to keep up with the common notion: survival of the fittest.

Source: Vanderbilt University via Science Mag, Experimental Biology

About the Author
  • Fascinated by scientific discoveries and media, Anthony found his way here at LabRoots, where he would be able to dabble in the two. Anthony is a technology junkie that has vast experience in computer systems and automobile mechanics, as opposite as those sound.
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