Page 2 - CrociduraWagler_Sara
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Downloaded by [] at 10:10 22 March 2014  were used as controls to evaluate the taxonomical distance among       CVA procedures. CVA seeks linear combinations of transformed
                                                        the other insular taxa.                                                morphometric variates that have greatest between-group variation
                                                                                                                               relative to their within-group variability. It is thus possible to trans-
                                                           The skulls found inside the pellets have their posterior part very  late the starting data on to a three-dimensional plane (canonical
                                                        often damaged. Of the 484 skulls formerly selected, it was possible    variate space) that best separates the OUT's centroids.
                                                        to measure five variates only in 10.33? of the whole sample, four
                                                        variates in 30.161 of the cases, three variates in 29.96Z, and two       The distance between the centroids was calculated by Mahala-
                                                        variates in 98.551. Moreover, in such remains the skull and the        nobis' generalized distances (D2). These are akin to phenetic dis-
                                                        mandibles were rarely found joined together. Since multivariate        tances but take some account of intraspecific variation and correla-
                                                        analysis requires the use of a complete set of data for each speci-    tion of characters (Jenkins, 1976). Significance levels of Mahalano-
                                                        men, the analysis of skull characters had to be excluded due to the    bis' distances were first expressed by Fisher's F test, later on by T2
                                                        limited amount of information available. Thus, we selected for the     Hotelling's transformation.
                                                        analysis only 480 right mandibles (see Table I for sample sizes of
                                                        each location). The following morphometric variates were mea-             Mahalanobis' distance matrix of mandible finally allowed the
                                                        sured on the mandible: total length excluding incisor (UKL),           association dendrogram of the OTU's considered to be displayed.
                                                        height at the coronoid process (COH), length of molars (MI-M3),        The method followed to construct the dendograms was derived
                                                        breadth of articular condylum (E).                                     from the sum of square groupings (Orloci, 1978).

                                                           The first step was to run principal component analysis (PCA);          Furthermore, we report the morphotypes graphic comparison of
                                                        this multivariate analysis is based on the correlation matrix corre-   the skull large upper premolar tooth (in occlusal view) and of the
                                                        sponding to the variance-covariance matrix of the standardized         posterior surface of the mandible condylar process. These char-
                                                        variates (Chessel & Auda, 1986).                                       acters have already proved useful in morphological discrimination
                                                                                                                               (Jenkins, 1976; Hutterer, 1986;.Molina & Hutterer, 1989).
                                                           The analysis seeks the interrelationships among the variates mea-
                                                        sured on each single specimen and allows the clustering of all the     RESULTS
                                                        specimens showing a similar pattern of interrelationship. The pur-
                                                        pose of the method is to give evidence of one or more clusters            The principal component analysis of mandible va-
                                                        (taxa) on each insular and peninsular sample.                          riates raised a single cluster for each insular and penin-
                                                                                                                               sular sample. In Table I, sample sizes, mean values,
                                                           To emphasize this aspect, the 265 mandibles coming from Sicily      and standard deviations of the morphometric variates
                                                        were not grouped together, but each location of pellet collection      considered are reported.
                                                        was considered to represent a separate «island». The samples from
                                                        Favignana and Levanzo were excluded from the PCA, due to their            Table II shows the discriminant coefficients of the
                                                        small size.                                                            canonical equations used to display each OTU on the
                                                                                                                               canonical space. The canonical coefficients statistically
                                                           The second step was to perform canonical variate analysis
                                                        (CVA), that maximizes separation between taxonomical units (Le-
                                                        gendre & Legendre, 1979).

                                                           In the study the group of specimens from each island is referred
                                                        to by the term operational taxonomic unit (OTU), according to the

                                                        TABLE I - Mandible biometry (mm) of the Crocidura OTU's from central Mediterranean islands and mainland Italy. Mean ± SD of length
                                                        mandible excluding incisor (UKL,), length ofmandible molars (M1-M3), breadth ofarticular condylum (E), andheight ofmandible at the
                                                        process (COH).

                                                        UKL       C. leucodon   C. suaveolens                                    C. russula    C. cl russula
                                                        M1-M3                                                                     Sardinia      Pantelleria
                                                        E           Italy           Italy                                         » = 99
                                                                   » = 12         » = 11                                                          » = 42
                                                        COH                                                                    10.55 ± 0.28
                                                               10.43 ± 0.33    9.33 ± 0.36                                      3.93 ± 0.11   10.93 ± 0.33
                                                        UKL     4.07 ± 0.09    3.55 ± 0.15                                      0.98 ± 0.06    4.06 ± 0.14
                                                        M1-M3   1.21 ± 0.09    0.96 ± 0.04                                      4.84 ± 0.14    0.92 ± 0.08
                                                                4.88 ± 0.18    4.20 ± 0.14
                                                        E                                                                       C. cf sicula   4.98 ± 0.18
                                                        COH       C. sicula       C. sicula                                      Marettimo
                                                                    Sicily         Gozo                                                         C. cf sicula
                                                        UKL                       »=17                                             » = 16         Ustica
                                                        M1-M3     » = 265                                                                         »=13
                                                        E                      9.94 ± 0.26                                     10.03 ± 0.27
                                                               10.47 ± 0.29    3.73 ± 0.11                                                    10.15 ± 0.35
                                                        COH     3.87 ± 0.14                                                     3.74 ± 0.09    3.69 ± 0.09
                                                                               0.90 ± 0.05                                                     0.91 ± 0.07
                                                                0.90 ± 0.09    4.36 ± 0.11                                      0.93 ± 0.04    4.56 ± 0.13
                                                                4.59 ± 0.15                                                     4.37 ± 0.13
                                                                                C. cf sicula
                                                                                Favignana                                       C. cf sicula
                                                                                    3.57                                            9.77
                                                                                   0.83                                             0.88
                                                                                   4.24                                             4.41
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