Whittaker 2002). Placing island ecological studies
into a scale framework, helps us reconcile appar-
ently contradictory hypotheses as actually being
relevant to different spatio-temporal domains
(Fig. 1.2, Haila 1990). We suggest that alongside
islands conforming to the dynamic, equilibrium
MacArthur–Wilson model, some islands may show
dynamic but non-equilibrial behaviour, while
other island biotas persist unchanged for substan-
tial period of time, constituting ecologically ‘static’
systems that can again be regarded as either equi-
librial or non-equilibrial. Island ecological theories
should also be capable of accommodating the hier-
archical links that form within ecological systems
(e.g. with respect to feeding relationships, pollina-
tion, dispersal, etc): this represents a considerable
challenge given a literature hitherto focused mostly
on pattern within a single trophic level, or major
taxon (mammals, birds, ponerine ants, etc.).
The three chapters in Part III, Island Evolution,
set out to develop the theme of island evolution
from the micro-evolutionary changes following
from initial colonization through to the full array of
emergent macro-evolutionary outcomes. In
Chapter 7, Arrival and change, we start with the
founding event on an island and work in turn
through the ecological and evolutionary responses
that follow from the new colonist encountering the
novel biotic and abiotic conditions of the island. A
series of traits, syndromes, and properties emerge
as characteristic of islands, including loss of disper-
sal powers, loss of flower attractiveness, the devel-
opment of woodiness, characteristic shifts in body
sizes of vertebrates, and rather generalist pollina-
tion mutualisms. These shifts are detectable to
varying degrees of confidence, and in a wide vari-
ety of taxa, sometimes but not always involving
attainment of endemic species status by the island
form.
The attainment of speciation, the emergence of
separate species from one ancestor, is of central
interest within biology, and so we devote Chapter
8,Speciation and the island condition, to a brief
account of the nature of the species unit, and of the
varying frameworks for understanding the process
of speciation. Thus, we examine first the geograph-
ical context of speciation, in which islands
conveniently provide us with a strong degree of
geographical separation between the original
source population and the island theatre, but in
which the extent of intraarchipelago and intrais-
land isolation is often harder to discern. Second, we
examine the various mechanistic frameworks for
understanding speciation events, and, finally, we
consider phylogenetic frameworks for describing
the outcome of evolutionary change. Having devel-
oped these frameworks, we go on to look at the
Emergent models of island evolution(Chapter 9),
which provide descriptions and interpretations of
some of the most spectacular outcomes of island
evolutionary change, including the classic exam-
ples of the taxon cycle and of adaptive radiation.
However, as more studies become available of phy-
logenetic relationships within lineages distributed
across islands, archipelagos, and even whole ocean
basins, new ways of looking at island evolution are
emerging. From this work it is becoming increas-
ingly evident that the ever-changing geographical
configuration and environmental dynamism of
oceanic archipelagos are crucial to understanding
variation in patterns and rates of evolutionary
change on islands.
Anthropogenic changes to biodiversity are evi-
dent across the planet, and we may turn to islands
for several important lessons if we care for the
future of our own human societies (Diamond 2005).
In the final section of the book, Islands and Conser-
vation, we start with the theme of Island theory and
conservation (Chapter 10), which debates the
contribution of island ecological thinking within
conservation science. As we turn continents into a
patchwork quilt of habitats, we create systems of
newly insularized populations. What are the effects
of fragmentation and area reduction within conti-
nents? Not just the short-term changes, but the
long-term changes?
As concern over this issue grew in the 1970s and
1980s, the obvious place to derive such theory was
from the island ecological literature, and in particu-
lar the dynamic equilibrium model put forward
by MacArthur and Wilson (1967). We review this
literature, showing that although we can often
develop good statistical models for the behaviour
of particular species populations, and for howTHE NATURAL LABORATORY PARADIGM 7