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, it is yet unclear what aspects of these shifts are fixed, and which may be due to phenotypic flexibility. There are few differences in digestive biochemistry in wild individuals measured from these populations. However, during lab feeding trials, lizards from the newly herbivorous population digested plant diets, and specifically the protein in those diets, more efficiently than did lizards from the source population. Fed insect diets, the two populations did not show differences in protein digestibility nor organic matter digestibility as a whole. What mechanism explains the newly herbivorous population’s increased digestive performance of plants proteins, compared to their source population counterparts? We are currently measuring digestive enzyme activities in the pancreas and proximal intestine of lizards from both populations that have been kept on experimental diets for up to a month. On the plant diet we expect to find increased protease activity in the in the new lizard population compared to the lizards from the source population, matching the digestibility findings. Our results may shed light on what functional and performance steps can initially lead to herbivory in lizards and the importance of phenotypic flexibility in this dietary shift.
