biosphere reserve Areas of terrestrial or coastal
ecosystems that are internationally recognized
within the framework of the UNESCO’s Man and
the Biosphere Programme (MAB).
biota All species of plants, animals, and microbes
inhabiting a specified region.
bottleneck A severe reduction in population
number that is often associated with reduced
genetic diversity and heterozygosity and reduced
adaptability of that population.
caldera A large crater (typically 5–20 km diame-
ter) formed by the collapse of a volcano following
withdrawal of magma from an underlying storage
chamber.
Cenozoic An era of geological time comprising
the Tertiary and the Quaternary periods, i.e. the last
65 million years.
character displacement The divergence of a
feature of two similar species where their ranges
overlap so that each uses different resources.
chequerboard distributionPattern shown by two
or more species that have mutually exclusive but
interdigitating distributions across a series of iso-
lates, such that each island (or habitat) supports
only one species.
clade Any evolutionary branch in a phylogeny,
especially one that is based in genealogical rela-
tionships.
cladogram (or phylogenetic tree) A line diagram
derived from a cladistic analysis showing the
hypothesized branching sequence of a monophyletic
taxon and using shared derived character states to
determine when each branch diverged.
cladogenesis Evolutionary change within a line-
age where the progenitor species is partitioned into
two or more lineages and becomes extinct.
coenocline Vegetation continuum along a gradient.
colonization The relatively lengthy persistence of
an immigrant species on an island, especially
where breeding and population increase are accom-
plished.
competition Negative, detrimental interaction
between organisms caused by their need for a com-
mon resource. Competition may occur between
individuals of the same species (intraspecific com-
petition) or of different species (interspecific com-
petition).
competitive exclusion The principle that when
two species with similar resource requirements
co-occur, one eventually outcompetes and causes
the extinction of the other.
connectance Fraction of all possible pairs of
species within a community that interact directly as
feeder and food. In other words, number of actual
connections in a food (or pollination) web divided
by the total number of possible connections.
conservation Human intervention with the goal
of maintaining valued biodiversity (genetic varia-
tion, species, ecosystems, landscapes, natural
resources).
continental fragments or micro-continents
Mainland fragments separated by tectonic drift
from their continents millions of years ago, with the
species they carried.
continental or land bridge islands Emergent
fragments of the continental shelf, separated from
the continents by narrow, shallow waters. This sep-
aration is often recent, as a result of the postglacial
rise of sea level, which isolated the species on the
island from conspecific mainland populations.
continental shelf The area of shallow sea floor
(200 m depth) adjacent to continents, underlain
by continental crust and effectively a submerged
extension of the continents.
convergent evolution Evolution of similar
features independently in unrelated taxa, usually
from different antecedent features or by different
developmental pathways.
corridor A dispersal route of favourable habitat
type, which permits the direct spread of species
from one region or habitat fragment to another.
counter-adaptation The evolutionary reaction of
an island’s native species to a newly arrived
species, such that over time they begin to exploit or
compete with the immigrant more effectively, thus
lowering its competitive ability.
crassulacean acid metabolism (CAM) plants
Usually succulent xerophytes in which carbon
dioxide taken up during the night is stored as malic
acid until fixed using the C 3 pathway the following
day.
cryptoturnover Turnover of species (extinction
followed by immigration) not detected because
occurring between two surveys.GLOSSARY 343