... studies of island biogeography show that a commu-
nity is not simply a collection of all those who somehow
arrived at the habitat and are competent to withstand the
physical conditions in it...a community reflects both its
applicant pool and its admission policies...We need to
formulate a new generation of population and commu-
nity models with the transport processes explicitly built
in...
(Roughgarden 1989, pp. 217–19, with thanks to
Thornton 1996)In Chapter 4, we took a macroecological approach
to island biotas: species were treated largely as
exchangeable units. Such an approach ultimately
has its limits. This chapter is therefore concerned
with those aspects of island biogeographic theory
dealing with compositional pattern and how it is
assembled (mostly) in ecological time. By consider-
ing the much more complicated response variable
of ‘composition’, it is possible to cast a different
light on to some of the problems left over from the
species numbers games (Worthen 1996). Pattern
interpretation in this chapter will again invoke
forces such as immigration, competition, and pre-
dation, but will also pay greater attention to species
autecology, dispersal attributes, and succession. In
essence then, whereas the previous chapter took a
macroecological approach, this chapter is con-
cerned with ecological biogeography.
Colonization and ecosystem development of a
not-too-distant island arguably constitute just a
special case of ecological succession, a process
(realistically many processes) that in complex
ecosystems, dominated by long-living organisms,
may be evident over hundreds of years. We illustrate
how succession can influence emergent patterns of
species numbers through the example of the recol-
onization of the Krakatau islands, which is not
only the best-studied ‘natural experiment’ in island
recolonization, but was also the first test system
used by MacArthur and Wilson (1967; see Wilson
1995). However, it is Jared Diamond’s theory that
provides the starting point for this chapter.5.1 Island assembly theory
Some readers may have experienced the daily
school assembly, the rules of which were that you
all stood quietly in lines, class by class, and
behaved yourselves while certain school rituals
were observed. Of course, these behavioural rules
were broken daily; furthermore, the precise order
and number of individuals in each line varied, but
on the whole the system approximated to the form
laid down. The casual observer looking in might,
however, have failed to recognize this on occasion.
This analogy might apply to island ecosystems, but
here detection of the rules, if they exist, requires a
great deal more application. This particular branch
of island ecology was given its impetus by an
extensive series of studies of the avifauna of New
Guinea and its surrounding islands by Diamond
(e.g. 1972, 1974, 1975a). The impetus was lost for
a while as the approach became embroiled in a
technical dispute concerning the formulation and
testing of hypotheses, and controversy concerning
the relative significance of competition in pattern107CHAPTER 5