Per una biogeografia dei sistemi trofici: il sistema "mammiferi terragnoli - Tyto alba" nell'Italia peninsulare e nelle isole maggiori

Abstract

B/OGEOGRAPHIA — vol. XI - 1985 Principi e rnetodi deII’anaIisi biogeografica Per una biogeografia dei sistemi trofici: il sistema «mammiferi terragnoli - Tyzfo czlba» nell’Italia peninsulare e nelle isole maggiori(qq‘) LONGINO CONTOLI (**), MARIA PIA SALUCCI (qqq') e AUGUSTO VIGNA TAGLIANTI (’”qq*) (qqq) Centro per la Genetica Ev0luzz'om'stz'ca, C.N.R., Via Lamcz'sz', 29 - 00161 Roma (*’qq*) Via Isole Eolie, 7 - 00141 Roma (’““qq‘) Dz'partz'mem‘o dz’ Biologic: Animale e dell’Uomo (Zoologia), Universz'tci di Roma «La Sapienza», Viale dell’Um'versz'tci, 32 — 00185 Roma SUMMARY Towards a biogeogmp/7y of trophic systems: the «terrestrial mammals - Barn Owl» systems in peninsular Italy and main islands. This work is aimed at the comparative evaluation of the role of historical versus ecological factors in outlining the regional features of trophic systems «terrestrial mammals - Tyto alba». The studied area is peninsular Italy and Corsica, Elba, Malta archipelago, Sardinia and Sicily islands. In such a perspective, we made a comparison between the above trophic qualitative patterns and faunistic ones, resulting from general faunistic knowledges on the small mammals. Among the above areas, two highly homogeneous clusters appear: the bigger one referring to the peninsular regions, exclusive of Apulia (expecially with respect to Barn Owl diets) and, even if to a lesser extent, of Eastern Liguria, the smaller one referring to the lesser islands. Sardinia is quite related to Sicily with respect to diets (perhaps due to vegetation being historically influenced in a similar way by human impact) and to smaller islands with respect to faunistic patterns, possibly heavily linked to man’s colo- nization and cultural flows. In general, the difference between the islands and peninsular Italy is much greater in faunistical comparisons than in trophic ones. Concerning the preyed mammalian taxa, the following groups (chorotypes) emerge: a) 4 entities widespread both in peninsula and in islands (Suncus etruscus, Apodemus (Sylvaemus) sp., Rattus rattus, Mus domesticus). With respect to trophic comparison, this group includes also Crocidura suaveolens; b) 7 entities everywhere present in peninsular Italy, but lacking from the islands (Sorex anmeus vel samniticus, Sorex minutus, Neomys cmomalus, Crocidura Zeucodon, Muscardinus auellamzrius, Arvicola ter- restris, Microlus (Pitymys) saviz); c) 2 «mesophilous» species bounded to the Po valley (Microtus arvalzs and Micromys minutus); cl) Microtus (Pitymys) multiplex, found in Apuane Alps; e) Crocidura russula, of Sicily, Sardinia and Maltese islands; f) Tzzlpa romamz, lacking from the northern part of peninsular Italy. The main difference between trophic and faunistic approaches are linked to the following species, all quite insulated as trophic components, due to their scarcity in Barn Owl diet: — Eliomys quercinus and Rattus norvegicus, linked to the «a» faunistic group; — Neomys fodiens and perhaps Cletbrionomys glareolus, linked to the «b» faunistic group. The patterns of the above species and of those of the «a» group seems to be related mainly to ecological factors; the other patterns are mainly due to historical factors. The overall overlap of trophic v.s faunistic spectra seems smaller in southern regions of peninsula and in Sicily. Trophic systems can establish themselves in a given area only if the habitat dimensions of ecological (*) Ricerche parzialmente eseguite con il contributo del C.N.R. (Gruppo Nazionale Biologia Naturali- stica, ctb. 85.00828.04) 211