Threats on Pacific islands: the spread of the Tramp Ant Wasmannia auropunctata (Hymenoptera: Formicidae)

Abstract

Since Elton (1958) highlighted the problem of biological invasions, numerous studies have established their importance in the structural evolution of natural communities, in particular insular communities. Because of their isolation, islands are regarded as natural evolution laboratories which are characteristically very fragile once the boundary is disturbed (McArthur and Wilson 1967; Williamson 1981; McDonald and Cooper 1995). This fragility is illustrated by the high proportion of species extinctions observed in islands: since 1600, more than 75% of monitored disappearances have been registered in islands (Goombridge 1992). Invasions are not an abnormality in the evolutionary process, but an increase in their rate could lead to a dramatic homogenization of fauna and flora.