Tropidurus catalanensis (Squamata, Tropiduridae) Lizards Consume Less Animal Matter When Dehydrated

Lizards of the genus Tropidurus typically exhibit an omnivorous diet composed predominantly of invertebrates, flowers, and fruits. The proportion of plant material in their diet varies significantly among individuals, populations, and species, with several hypotheses proposed to explain the environmental factors driving this variation. In this study, we tested if plant material consumption increases with dehydration, supporting the hypothesis that environmental aridity promotes greater reliance on plant-based food. To test this hypothesis, we housed individuals of Tropidurus catalanensis in the laboratory and submitted the lizards to different 10-d treatments: one group was deprived of both food and water, while the other had access to water but no food. After the treatment period, all lizards were offered food equivalent to 10% of their body weight, consisting of 5% mango pieces and 5% cockroaches, for 24 h. Leftovers were weighed to quantify consumption, and lizards were then returned to terraria with ad libitum food and water for a 5-day recovery period. The experiment was then repeated with treatments reversed for each group, ensuring all lizards experienced both conditions. Our results revealed no significant difference in mango consumption between hydrated and dehydrated lizards; however, dehydrated lizards consumed fewer cockroaches, resulting in a higher proportion of mango in their diet (75%) than in the diet of hydrated lizards (53%). These findings demonstrate how short-term physiological changes, such as dehydration, can influence individual dietary preferences and alter food selection. This study suggests that plant consumption could be more common in drier environments because plant-based foods require less water for digestion, whereas high-fat and high-protein items become less viable for large-scale consumption under dehydrating conditions.