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P. 5  Page 5  Thursday, December 27, 2001  10:00 AM

                                                                               Mammals from Mediterranean islands  5

                                    Oryctolagus cuniculus
                                        Genetta genetta
                                          Microtus savii
                                           Rattus rattus
                                          Ovis orientalis
                                     Erinaceus europaeus
                                     Apodemus sylvaticus
                                         Mustela nivalis
                                       Crocidura russula
                                           Dama dama
                                         Cervus elaphus
                                          Vulpes vulpes
                                            Sus scrofa
                                      Apodemus flavicollis
                                         Capra aegrarus
                                         Lepus capensis
                                       Eliomys quercinus
                                           Myoxus glis
                                           Meles meles
                                           Mus spretus
                                        Mus domesticus
                                  Muscardinus avellanarius
                                        Lepus europaeus
                                         Acomys minous
                                          Martes martes
                                       Lepus corsicanus
                                           Martes foina
                                          Canis aureus
                                            Lutra lutra
                                     Crocidura suaveolens
                                          Felis silvestris
                                                      2            1             0             –1            –2
                                                                      Residuals of mammal density

                                 Fig. 2 Residuals of mammal density corrected for mammal body mass and phylogeny using the eigenvectors
                                 method (see Material and methods).

                                 less significant using independent contrasts (OLS
                                                                          Density and island area size
                                 slope = – 0.52 ± 0.24,  r = 0.38,  P = 0.012).
                                   Using the eigenvector method, we found a  We controlled the contrasts in host density for
                                 phylogenetic effect for the relationship between  the contrasts in body mass by using residuals of
                                 density and body size, as depicted by linear  the linear regression between the two variables.
                                 correlation between these traits and the two  We found a significant negative relationship
                                 first eigenvectors of the phylogenetic matrix  between the area size of islands and the residuals
                                 (Table 2). The slope of the partial regression  of host density using independent contrasts
                                 (–0.51 ± 0.11) was not significantly different to  (Fig. 3, P = 0.024). This relationship was signi-
                                 those obtained by the independent contrasts  ficant using cross species values (r = – 0.439,
                                 method.                                  P = 0.015). Using the eigenvectors method, a
                                   The residuals of density, corrected for the  similar and significant relationship was found
                                 two first eigenvectors and body mass, are given  between the residuals of density (Fig. 2) and the
                                 on Fig. 2. The mammal species with high  area of island (r = – 0.406; P = 0.023). We found
                                 residuals values are then hypothesized to have  no effect of geographical distance on residuals of
                                 high abilities to maintain themselves in small  host density using independent comparisons
                                 islands.                                 (P = 0.09).
                                 © 2002 Blackwell Science Ltd, Diversity and Distributions, 8, 1–9
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