Page 7 - capula_eal2009
P. 7

MORPHOLOGICAL VARIATION IN INSULAR LACERTID LIZARDS       223

                                                          would indicate the occurrence of highly divergent
                                                          individuals in the population. As it is evident from fig. 8,
                                                          Podarcis raffonei is the most variable species. In
                                                          particular, the sample from Scoglio Faraglione (R3)
                                                          shows the highest variability and is morphologically
                                                          differentiated from the samples of Strombolicchio (R2)
                                                          and Vulcano (R4).

Fig. 5 Digitalized images of the cephalic scales of P.    DISCUSSION
sicula, P. wagleriana, and P. raffonei. Parietal (white       Landmark based morphometrics applied to the
square) and Sopraocular (white asterisks) scales were
found to be diagnostic for the three species. The skulls  analysis of the cephalic scales of Podarcis raffonei, P.
are equal in size to allow comparison of shapes.          sicula, and P. wagleriana was found to be a powerful
                                                          tool in the detection of the pattern of geographic
analysed samples show high morphometric variation (cf.    variation and the phenetic relationships among and
fig. 8). In particular, the sample from Zingaro (Sicily,  within species. The three species significantly differ
W1) shows a very reduced morphometric variability and     from each other in both shape and size of the skull.
is morphologically differentiated from all other          Podarcis sicula is characterized by narrow and long
populations. On the other hand, the sample from the       rostral and nasal regions. On the contrary, in Podarcis
small island of Marettimo (W8) is characterized by a      wagleriana the rostral and nasal regions are wider and
number of outliers and extremes of variation which        shorter than in P. sicula. In Podarcis raffonei the shape
                                                          of the skull is intermediate between P. sicula and P.
                                                          wagleriana. The shape of the Parietal and Sopraocular
                                                          scales appears to be highly diagnostic and species-
                                                          specific, thus representing a useful tool for recognition
                                                          of the species (cf. fig. 5): they are much larger and wider
                                                          in Podarcis sicula than in P. wagleriana, while in P.
                                                          raffonei the shape of these scales is intermediate between
                                                          P. sicula and P. wagleriana.

                                                              Size is another important component of interspecific
                                                          variation. The three species are characterized by
                                                          different allometric static patterns, as revealed by the
                                                          relationship between size of the skull and body length.
                                                          Podarcis wagleriana is characterized both by a smaller
                                                          head and body length, while P. sicula has a larger head
                                                          and body length which is intermediate between P.
                                                          wagleriana and P. raffonei. Podarcis raffonei shows the
                                                          largest body length, but its head size is intermediate
                                                          between P. sicula and P. wagleriana.

                                                              According to the results of landmark based
                                                          morphometrics and biometric analysis, P. sicula and P.
                                                          wagleriana appear to be relatively differentiated from
                                                          each other, while P. raffonei seems to be phenetically
                                                          intermediate between P. sicula and P. wagleriana. It
                                                          must be noted that phenetic analyses are partially
                                                          congruent with allozyme and molecular investigations
                                                          (Capula, 1994a; Harris & Arnold, 1999, Vasconcelos et
                                                          al., 2006), which indicate that Podarcis sicula is
                                                          genetically differentiated from both P. wagleriana and P.
                                                          raffonei, and that Podarcis raffonei is genetically closely
                                                          related to P. wagleriana.

                                                              The analysis of the intraspecific variation in shape of
                                                          the cephalic scales indicates that P. sicula is the less
                                                          variable species. This pattern is evident both in the
   2   3   4   5   6   7   8   9   10   11   12