Fróðskaparrit - 01.01.1987, Side 61

WHEN, HOW, AND WHENCE?
65
a large species pool), but that the subse-
quent inner colonization may be rather
slow, if immigration from the source pool
ceases and the further colonization of the
island group becomes (mainly) dependent
on dispersal from the populations which
have established themselves in (perhaps a
few) beach-heads.
My belief is that this is what happened
for a number of species after the initial lar-
ge-scale immigration during the first Post-
Glacial dispersal event. This large-scale
immigration ceased after some time and
left the further spread of the taxa over the
islands to the already established popula-
tions. Some of the species distribution pat-
terns we have found in the Faroes indicate
that the dispersal process within the islands
is still not completed.
This general overview is, however, not
the place to discuss individual species, or
differences within larger taxonomical
groups when it comes to colonizing the
Faroe Islands. Some such patterns are
treated in fuller detail in Enchell et al.
1986.
Acknowledgements
I thank S.-A. Bengtson for many fruitful and stimulat-
ing discussions about the history of the Faroese biota,
and S. Douwes for help with the figures. D. Bloch as-
sisted in various ways during field and laboratory work.
We acknowledge the assistance of Støðisútbúgvingin
(Academia Faeroensis) and the Natural History Muse-
um in Tórshavn for laboratory and logistical facilities
and support. The Swedish Natural Science Research
Council is acknowledged for financial support (to S. -A.
Bengtson).
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