Encyclopedia of biodiversity encyclopedia of biodiversity, (7 volume set) ( PDFDrive ) 2748

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Island Biogeography

mathematical model. However, the model is easily understood
from Figure 1. For example, a large archipelago, such as the
Fijian Islands, situated nearer to continental source areas for
the dispersion of biota, would have richer species equilibria
than a large archipelago, such as the Hawaiian Islands, which
is much farther removed from any biotic source area.
The reality of species equilibria is highly questionable, yet
the theory has been and continues to be very inspirational. If
applied not simply to species per se, but instead to different
life forms, such as indigenous trees, ferns, or shrubs, the results may show differing values of species richness and endemism in relation to size of island areas and degrees of

Figure 1 The MacArthur and Wilson (1963, 1967) models of
dynamic species equilibria as controlled by distance of islands from
biotic source areas (from near to far) and by size of islands (from
small to large). Reproduced from MacArthur RH and Wilson EO
(1963) An equilibrium theory of insular zoogeography. Evolution 17:
373–387 and MacArthur RH and Wilson EO (1967) The Theory of
Island Biogeography. Princeton, N.J.: Princeton University Press.

Table 1

isolation. Moreover, these in turn may lead, with additional
ecological studies, to a better understanding of the function of
biodiversity in different island ecosystems.
At this point, another limitation of this theory should
be mentioned. This relates to the fact that size of island area
is only a most general predictor of species richness. At least

elevational range and substrate type should be added to make
the theory more predictable. This brings us to the next theory.

The Biome Theory
This theory predicts that there are broad life zones that are
indicated by groups of biota of key plant life forms, which are
controlled by certain broad-area climatic and edaphic (soil)
parameters. For example, the biome theory predicts that in
mountainous environments there are altitudinal life zones
(Holdridge, 1967) or vegetation zones (Mueller-Dombois and
Ellenberg, 1974) that can be distinguished by tree species and
other life forms into lowland, upland, and high-altitude
zones. Also, such familiar terms as desert, grassland, deciduous
forest, coniferous forest, and tundra depict different latitudinal
biome types, which in turn can be defined by climatic parameters as ‘‘zonobiomes’’ (Walter et al., 1975). It is assumed
that conditions for life within a biome are more homogenous
than life conditions across different biomes (such as grassland
versus desert).
Applied to island biogeography, the biome theory lends
itself to a more appropriate refinement in the analysis of biodiversity than is offered by the two ecosystem parametersFsize
and isolationFin the above described theory of island biogeography. For example, comparative biodiversity research
within a Pacific-wide biome type, such as the montane rain
forest on volcanic high islands of basaltic origin, is scientifically more satisfying than biodiversity research based simply
on size of island area. The size approach groups different types
of islands into the same category, which thus can be a very

Areas of specialization within the field of Geobotany, their synonyms, and Anglo-American equivalents

Area of specialization (and synonyms,
European terms)

Subject matter

Anglo-American equivalents (and
synonyms)

Floristic geobotany

Study of geographic distribution of plant taxa and their
evolutionary relationships
Study of composition, development, geographic
distribution, and environmental relationships of plant
communities

Plant geography (phytogeography)

Sociological geobotany (vegetation
science, plant sociology, phytosociology,
phytocoenology)
Ecological geobotany (plant ecology)
Autecology (ecophysiology)

Demecology (population ecology)
Synecology (habitat science; ecosystem
research)

Historical geobotany

Study of physiological functions of individual organisms
in the field environments and communities; life-history

studies of species or ecotypes
Study of structure and function of populations
Study of genetic variation in populations
Study of habitat factors and the physiological response of
species and species groups to these factors; study of
community functioning, and niche functions of plant
populations in an ecosystem context
Study of historical origins and development of
populations and communities

Synecology (community ecology,
plant ecology in part)

Autecology (physiological ecology,
population ecology in part)
Population ecology
Genecology
Ecosystem ecology (community
process ecology, functional
ecology, systems ecology)
Paleobotany (paleoecology)

Source: Reproduced from Mueller-Dombois D and Ellenberg H (1974) Aims and Methods of Vegetation Ecology. New York: John Wiley & Sons.