Here I advocate a comparative and systematic approach in which invasio
n (the extension of species ranges to areas not previously occupied by
that species) is studied from the perspective of individual species a
s well as of the regions and biotas that export and receive invaders.
In order to go beyond the particulars of invasion, it is important to
ask: (1) how invaders differ from noninvaders in the arrival, establis
hment, and integration phases of invasion; (2) how donor regions or co
mmunities that have produced many successful invaders differ from thos
e in which few resident species have been able to extend their ranges;
(3) how recipient ecosystems with many successfully established invad
ers differ from those in which few species have taken hold; and (4) ho
w invasion affects evolution not only of the invader itself but of spe
cies in the recipient community with which the invader interacts. Copy
right (C) 1996 Elsevier Science Limited