# RES

Project Title: Genomic Aspects of Rapid Evolution in the Italian Wall Lizard (Podarcis siculus)

Partners: Faculty of Science, University of Zagreb

Project Duration: 2016 – 2021

Status: Completed

Species: Italian Wall Lizard (Podarcis siculus)

IUCN Red List Status: Least Concern (LC)

National Red List Status in Croatia: Least Concern (LC)

Project Overview:

The Genomic Aspects of Rapid Evolution in the Italian Wall Lizard project was established to explore the genetic foundations underlying evolutionary changes in populations of the Italian wall lizard (Podarcis siculus). Rapid evolution is a fascinating biological phenomenon in which adaptive traits emerge and become noticeable within just a few generations.

A notable instance of such rapid evolutionary change occurred in 1971, when five pairs of Italian wall lizards were relocated from the islet of Pod Kopište to the nearby island of Pod Mrčaru, part of the Lastovo archipelago in the Adriatic Sea. Pod Mrčaru had no prior population of this species, and the transplanted lizards were exposed to different environmental conditions. Over the ensuing decades, these conditions led to significant changes in their morphology and behavior.

Research that began in 2004 uncovered several phenotypic differences between the lizards on Pod Mrčaru and their original counterparts on Pod Kopište. Notably, the Pod Mrčaru lizards, adapting to a diet richer in plant material, developed larger and more robust teeth, a modified jaw structure, and, remarkably, cecal valves—an anatomical digestive feature not previously observed in this species.

The primary goal of this project is to identify the genetic mechanisms driving these changes and to determine whether they represent true evolutionary adaptations to a new environment or are simply the result of phenotypic plasticity.

Zagreb Zoo provided specialized facilities to house and care for lizards in environments tailored to reptilian needs, actively supporting crossbreeding experiments. Our team ensured that individuals from both Pod Kopište and Pod Mrčaru populations were kept under controlled conditions and underwent a period of acclimatization prior to breeding. The “common garden” experiment, conducted at the Zoo, enabled researchers to assess the heritability of various phenotypic traits in this species.

Leveraging our expertise in maintaining reptiles in regulated environments, our specialists successfully facilitated experiments requiring particular attention—especially in managing territorial males and organizing female groupings.

The research yielded important insights into the pace of evolutionary change. Findings revealed that phenotypic traits related to head morphology, such as jaw size and structure, exhibit moderate to high heritability. Genomic analyses further confirmed that the Pod Mrčaru and Pod Kopište populations are genetically distinct, identifying 18 loci likely under selection and associated with differences in phenotype and ecological adaptation. These traits reflect strong selective pressures, particularly those faced by Pod Mrčaru lizards as they adapted to new dietary and environmental conditions.

Moreover, the research conducted at Zagreb Zoo demonstrated that phenotypic divergence is shaped not only by environmental factors but also by a substantial genetic component. These findings suggest that rapid environmental changes can lead to significant genomic responses over relatively short timescales—a discovery especially relevant in the current era of accelerating ecological transformation.

Summary:

The project “Genomic Aspects of Rapid Evolution in the Italian Wall Lizard” investigated the genetic foundations of rapid evolutionary change in the Italian wall lizard (Podarcis siculus) following its relocation to a new island environment. The study uncovered notable morphological and genetic adaptations linked to shifts in diet and habitat, demonstrating how evolutionary changes can occur within a short timeframe.