Zoogeography aims to explain the structure, function and history of the
geo- graphical ranges of animals. The absence or presence of a species
in a given place has ecological as well as historical causes. It is
therefore a mistake to suppose that reconstructing the phylogenetic
connections of a taxon will by itself give a definite picture of how its
range originated. A purely ecological interpretation of the range could
be equally misleading if it did not take into account the
population-genetic structure underlying the geographical range.
Phylogenetic systematics, population genetics, autecology and synecology
have all their own methods, none of which can be substituted for
another, without which a range cannot be studied or interpreted. The
present book covers only certain aspects of the wide field of zoogeo-
graphy. These are in the form in which they were crystallised in the
course of innumerable discussions with my teachers, my colleagues at
home and abroad and my fellow workers, postgraduates and students at
Saarbriicken, as well as in the zoogeographical part of may basic
lectures on biogeography for the year 1973-1974. The chief emphasis is
laid on the genetic and ecological macro- structure of the biosphere as
an arena for range structures and range dynamics, on urban ecosystems,
which have hitherto been grossly neglected, and on the most recent
history of ranges (the dispersal centre concept). The marine and
fresh-water biocycles, on the other hand, have been dealt only briefly.
