The Intriguing Biogeographic Pattern of the Italian Wall Lizard Podarcis siculus (Squamata: Lacertidae) in the Tuscan Archipelago Reveals the Existence of a New Ancient Insular Clade

Animals (Basel). 2023 Jan 23;13(3):386. doi: 10.3390/ani13030386.

Abstract

The Tuscan Archipelago is one of the most ancient and ecologically heterogeneous island systems in the Mediterranean. The biodiversity of these islands was strongly shaped by the Pliocene and Pleistocene sea regressions and transgression, resulting in different waves of colonization and isolation of species coming from the mainland. The Italian wall lizard, Podarcis siculus, is present on the following islands of the Tuscan Archipelago: Elba, Giglio, Giannutri, Capraia, Montecristo and Cerboli. The species in the area displays a relatively high morphological variability that in the past led to the description of several subspecies. In this study, both the genetic and morphological diversity of P. siculus of the Tuscan Archipelago were investigated. Specifically, the meristic characters and the dorsal pattern were analyzed, while the genetic relationships among these populations were explored with mtDNA and microsatellite nuclear markers to reconstruct the colonization history of the Archipelago. Our results converge in the identification of at least two different waves of colonization in the Archipelago: Elba, and the populations of Cerboli and Montecristo probably originate from historical introductions from mainland Tuscany, while those of Giglio and Capraia are surviving populations of an ancient lineage which colonized the Tuscan Archipelago during the Pliocene and which shares a common ancestry with the P. siculus populations of south-eastern Italy. Giannutri perhaps represents an interesting case of hybridization between the populations from mainland Tuscany and the Giglio-Capraia clade. Based on the high phenotypic and molecular distinctiveness of this ancient clade, these populations should be treated as distinct units deserving conservation and management efforts as well as further investigation to assess their taxonomic status.

Keywords: Mediterranean; Podarcis siculus; Tuscan Archipelago; biogeography; insular lizards.

Grants and funding

This research and the APC was funded by: Parco Nazionale dell’Arcipelago Toscano and Italian Ministry of Environment (prot. 0034731 of 09/11/2012, prot. 0001805 of 04/02/2015, 68754 of 28/11/2016, prot. 67681 of 27/11/2018); Ministry of University and Research of Italy (MUR), project FOE 2020—Capitale naturale e risorse per il futuro dell’Italia—Task Biodiversità; “Progetti di Ricerca Sapienza”, grant numbers RP11916B6F67B141 and RP11816430E2E16A.