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The Expansion-Contraction (EC) model predicts demographic and range contraction of temperate species during Pleistocene glaciations as a consequence of climate-related habitat changes, and provides a paradigm for explaining the high intraspecific diversity found in refugia in terms of long-term demographic stability. However, recent evidence has revealed a weak predictive power of this model for terrestrial species in insular and coastal settings. We investigated the Pleistocene EC dynamics and their evolutionary consequences on temperate species using the Maltese archipelago and its endemic lizard Podarcis filfolensis as a model system. The evolutionary and demographic history of P. filfolensis as inferred from mitochondrial and nuclear sequences data does not conform to the EC model predictions, supporting (i) demographic and spatial stability or expansion, rather than contraction, of the northern and southern lineages during the last glacial period, and (ii) a major role for allopatric differentiation primed by sea-level dynamics, rather than prolonged demographic stability, in the formation of the observed genetic diversity. When combined with evidence from other Mediterranean refugia, this study shows how the incorporation of Pleistocene sea-level variations in the EC model accounts for a reverse demographic and range response of insular and coastal temperate biotas relative to continental ones. Furthermore, this cross-archipelago pattern in which allopatric diversity is formed and shaped by EC cycles resembles that seen between isolated populations within mainland refugia and suggests that the EC model, originally developed to explain population fluctuations into and out-of refugia, may be appropriate for describing the demographic and evolutionary dynamics driving the high genetic diversity observed in these areas.

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The Maltese Wall Lizard, Podarcis filfolensis, exists in a number of isolated populations, some of which have been given formal scientific names as subspecies. Special attention was given to the population of P.filfolensis kieselbachi, which is endemic to Selmunett Island due to the fact of its rapid decrease. The prime suspect for this matter is Rattus sp. Through the literature read it was noted that between the late 80`s to early 90`s, the population of P.filfolensis kieselbachi was very dense all over the island. Since the present author started visiting the island in late 1997, there was still quite a good stable population that scarcely could be found in all over the island. During these studies since 1999 the author divided the island in several sections in order to organise my observations. Today, lizards inhabit approximately only 1/10 of the island and they are all located in one particular section of the smaller islet that the author have designated as Area C. Here the maximum population is of the order of 30 to 35 lizards. This very small population is a matter of concern and some kind of action has to be taken to reverse this decline.

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The Maltese Wall Lizard Podarcis filfolensis has long fascinated biologists due to its remarkable phenotypic plasticity and island-specific traits. Historically, the species was divided into multiple subspecies based on morphology, a framework that persisted unchallenged for most of the 20th century. However, contemporary genetic studies undermine the subspecies model, instead revealing two major clades across the Maltese and Pelagian Islands. This paper reviews historical and modern taxonomic interpretations, presents detailed morphological field observations, and critiques the persistent misuse of outdated subspecies nomenclature in both academic and public discourse. We advocate for the recognition of island morphs within a single species model and call for institutional leadership in taxonomic modernization.

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The islet’s recent discovery by the authors hold quite a rich biota compared to its size. In this work topography is re- described adding one species of flora to the already known six (SCIBERRAS & SCIBERRAS 2010, SCIBERRAS et al. 2012) and 32 new species of fauna to the two recorded (LO CASCIO & SCIBERRAS 2020, AGUIS & SCIBERRAS 2022) with a complete description of the endemic lacertid, Podarcis filfolensis, in situ.