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摘要
We analysed the species-area relationship and structural connectivity among islands of La Maddalena Archipelago (Italy), a numerous group of small islands very close to Sardinia. We related species richness (amphibians and reptiles) to several environmental factors (area; number of unique habitats; topographical variables; and distances of each island to Sardinia, to the nearest island and to the nearest large island) using generalized additive models and connectivity analysis by graph theory and the software Conefor 2.6. Using each method, we performed several comparisons: considering all species; excluding species with a high exchange rate ('in transit'); including only autochthonous species; and including species present on large islands. We also excluded, in turn, all amphibians; all Scincidae; all Gekkonidae; all Lacertidae; all Colubridae; and one species in turn. Except in the case of species present on large islands, all models selected the same variables: ruggedness standard deviation, area, number of unique habitats, and mean and maximal elevation. When excluding Sardinia, the highest connectivity value corresponded to the largest islands. Species richness is related to island complexity (habitat diversity and topographical complexity) and not simply to area. Network connectivity is dominated by the internal connectivity of the largest islands, but small islands are essential to maintain the network connectivity and endemicity.
- 出版日期2018-5
