Meeting Abstract
A population of Italian Wall Lizards (Podarcis sicula) in Croatia has become primarily herbivorous and morphologically distinct from its source population in ~30 generations, making it a compelling example of rapid evolution. However, we know little about what these lizards are capable of digesting from plant material, and whether their physiology is optimized for a plant diet. During lab feeding trials, lizards from the newly herbivorous population digested the organic matter of plant diets more efficiently than did the naturally insectivorous lizards from the source population. However, the two populations did not show differences in digestive efficiency of an insect diet. What mechanism explains the newly herbivorous population’s increased digestive performance of plants compared to their source population counterparts? By investigating what nutrients each population is assimilating from their diets, we can better understand the interplay of gut function and digestive performance. We measured both lizard populations’ digestive efficiency of protein, carbohydrates, and lipids. If nutrient digestibility is matched to gut function, we should be able to predict what nutrients are assimilated based on digestive enzyme activities in wild lizards. We expect the newly herbivorous population digests carbohydrates more efficiently, as their free living counterparts have higher activities of carbohydrases in some gut regions. We also expect the newly herbivorous population is slightly more efficient at protein digestion, as trypsin activity is higher in their hindguts. Analyses of macronutrient digestion are underway. As this is a study of lizards that have diverged recently, our results may shed light on what functional and performance steps can initially lead to herbivory in lizards.
