engleski

Species/area and other relationships in land snail (Mollusca: Gastropoda terrestria) faunas of some Adriatic islands

Data from a number of surveys of land snails on islands off the Adriatic coast of Croatia are used to investigate the nature of the island species-area relationships (ISARs) both among larger islands and, in greater detail, among 83 islets in the Kornati archipelago. These islands and islets are all continental, and separated from the mainland no more than 10, 000 years ago. In both cases there are significant positive ISARs, but in the case of the islets the slope of the log/log regression is shallow (z = 0.131) relative to most reported ISARs from elsewhere. Island area and altitude are very strongly correlated, and it is impossible to distinguish between an effect due to area alone and one related to a greater range of habitats on higher islets. Despite the very small size of some islets, there is no evidence for any Small Island Effect. Increasing isolation does not result in impoverishment. Snail species differ in the extent to which they are more likely to occur on large islands ; while many show a strong association with island area, others, especially some not restricted to rocks, do not. The faunas are not strongly nested and some species found on small islets are not found on some larger ones, or on the much larger Kornat Island itself. Single site faunas on small islets are not much poorer than those from single sites on larger islands. We interpret the pattern as being mainly the product of long-term survival through the period of island formation, but we cannot rule out the possibility of some passive transport by humans.

land snails; Adriatic; islands; island species-area relationship (ISAR); Small Island Effect (SIE)

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