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ALDROVANDIA 5 2009: 217 - 227

SIZE AND SHAPE IN MEDITERRANEAN INSULAR LIZARDS: PATTERNS OF VARIATION IN
PODARCIS RAFFONEI, P. SICULA AND P. WAGLERIANA (REPTILIA: SQUAMATA: LACERTIDAE)

Massimo Capula, Sara Chiantini, Luca Luiselli, Anna Loy

ABSTRACT Landmark based geometric morphometrics was applied to the analysis of the cephalic scales of three
phylogenetically related lacertid lizards (Podarcis raffonei, P. sicula, P. wagleriana) from some islands of the central
Mediterranean area in order to assess the pattern of geographic variation and the phenetic relationships among and within the three
species. Twenty nine homologous landmarks were recorded on the half configuration of the cephalic scales. To compare geometric
and biometric patterns of variation and to evaluate any static allometry, seven biometric measurements were also recorded on the
whole body. The three species significantly differ from each other in both shape and size of the skull. The shape of the Sopraocular
and the Parietal scales appears to be highly diagnostic and species-specific. The analysis of intraspecific variation in shape of the
cephalic scales indicates that P. sicula is the less variable species within the studied geographic area, whereas Podarcis raffonei is
the most variable species both in size and shape. Podarcis raffonei is characterized by a divergent allometric pattern, likely related
to the small population size and highly fragmented geographic range of the species.

KEY WORDS Geometric morphometrics, biometry, geographic variation, Podarcis, Lacertidae, Sicily

INTRODUCTION number of Tyrrhenian and Adriatic islands (Henle &
The genus Podarcis Wagler, 1830 comprises 20 Klaver, 1986; Corti & Lo Cascio, 2002). Podarcis sicula
appears to be an efficient colonizer, as it has been
currently recognized species. Most of the species occur in successfully introduced and acclimatized to several
southern Europe, where they are the predominant reptile extralimital areas (cf. Capula, 1994b; Corti & Lo Cascio,
group in terms of biomass (Harris & Arnold, 1999). Many 2002 for an updated list of localities). Podarcis
studies have been devoted to investigate genetic and wagleriana is endemic to Sicily and some small satellite
molecular variation in several species of this genus (e.g. islands (Egadi Islands and Stagnone Islands) (Arnold &
Capula, 1994a, 2004; Oliverio et al., 1998; Harris & Ovenden, 2002; Corti & Lo Cascio, 2002; Capula,
Arnold, 1999; Capula & Ceccarelli, 2003; Poulakakis et 2006b), and is broadly sympatric with P. sicula. The three
al., 2003; Arnold et al., 2007; Caputo et al., 2008), while species are anatomically and ecologically similar (cf.
only a few data are available about the pattern of Lanza, 1968; Sorci, 1990; Capula, 1992; Arnold &
morphometric variation of some species (e.g. Bruner & Ovenden, 2002; Corti & Lo Cascio, 2002; Capula &
Costantini, 2007; Kaliontzopoulou et al., 2007). The Ceccarelli, 2006). Their colour patterns are also similar,
insular Mediterranean Podarcis lizards seem to be but P. raffonei typically has dark markings on the throat,
particularly useful for the analysis of morphological while P. sicula has a throat which is normally white and
variation - which can highlight microevolutionary unspotted (Arnold & Ovenden, 2002; Corti & Lo Cascio,
processes of divergence and adaptation (cf. Heywood, 2002). Podarcis wagleriana has a throat which is
2000) - because they are normally characterized by high generally salmon red and, in some cases at least (e.g.
inter- and intra-population morphological variability (e.g. Marettimo Island populations), it may have dark
Arnold & Ovenden, 2002; Corti & Lo Cascio, 2002). markings. Therefore, morphological identification of the
species may be difficult, especially in the areas where
In this paper we investigate the morphometric they coexist (e.g. Sicily and Egadi Islands, where P.
relationships among three phylogenetically related sicula and P. wagleriana occur sympatrically, and
lacertid lizards of the genus Podarcis occurring on some Vulcano Island, where P. sicula and P. raffonei are known
islands of the central Mediterranean area, i.e. P. raffonei to coexist). In spite of this, no comparative morphometric
(Mertens, 1952), P. sicula (Rafinesque, 1810) and P. investigation has been carried out on the above
wagleriana Gistel, 1868. Podarcis raffonei is endemic to mentioned species to date.
the Aeolian Islands, where it is sympatric with P. sicula
on Vulcano Island (Capula, 1994a, 2004; Corti & Lo To assess the pattern of geographic variation and the
Cascio, 2002). Podarcis raffonei has recently received relationships among and within the three species,
attention because it is threatened with extinction (Capula geometric morphometrics of the cephalic scales was
et al., 2002; Capula, 2004, 2006a; Capula & Lo Cascio, compared with traditional biometry. Geometric
2006). Podarcis sicula occurs in peninsular Italy, in morphometrics has several advantages over traditional
Sicily, along the Adriatic coast of Dalmatia and in a