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BIOGEOGRAPHY: DOES
THEORY MEETPRACTICE?
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Are we experiencing biodiversity crisis?
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Mass Extinctions
Ordovician
Devonian
Permian
Triassic
Cretaceous
Quaternary
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The 7th Mass Extinction
Holocene (present)
Anthropogenic cause
Depletion of natural resources
“The human population is
approaching the limit at which
an acceptable quality of lifefor its entirety can be
attained”
Wilson 1999
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Outline
An Insular Science
Patterns and Priority
Theory Into Practice: Problems and Prospects
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An Insular Science
Islands
Parcels of land surrounded by ocean
Facilitates several unusual evolutionary trends
Increased insularity and isolation is a major factorin accelerating species decline
Primary productivity by humans results in anincreasingly fragmented and compartmentalized
earth in which insularization of communitiesbecomes the norm leading to higher risk ofextinction
Persian carpet analogy (Quammen 1999)
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Patterns and Priority
Conservation
Hotspots: islands of exceptional species richnessand endemism 25 documented global hotspots
44% of all species of vascular plants
35% of all species of four vertebrate groups
Confined to 1.4% of the terrestrial land surface of the earth
3 Key Strategies (Fonseca 2000)
Improved quantity and quality of data Enhanced collaboration with scientists
Closer co-operation with decision makers
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Patterns and Priority
Reserve Selection
Bibby (1998)
Including a species at least once
≥95% chance of including a community at least once Representing each land system at least once
Wessels et al. (1999)
Land facets (simple units of a landscape with uniform
slope, soils, and hydrology)
Heterogeneity and biological richness are not always
correlated.
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Patterns and Priority
Reserve Selection
Shafer (1999)
Complex criterion of ‘scenery’ may have been a
significant part of the decision-making process
Species-based approaches are themselves sometimes
flawed because they may fail to account the
multidimensional nature of biodiversity.
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Patterns and Priority
Reserve Selection Maddock and du Plessis (1999) Use ecological or biogeographical zones
Turpie et. al. (2000)
Rarity algorithm – focused on the rare and endemic Greedy algorithm – focused on the total number of species
Ideal Reserve Network Optimum distribution of frequency of areas needed to
maintain one at least one population of each species
Selection of each new site is dependent on the previouslyselected site
Irreplaceability – occurrence of narrow endemics or aparticular combination of species is regarded irreplaceable
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Theory Into Practice: Problems and
Prospects
Equilibrium Theory of Island Biogeography
(MacArthur and Wilson 1967)
Species richness on an island
represents a dynamicequilibrium controlled by the
rate of immigration of new
species and the extinction of
previously established
species.
www.colorado.edu
Most of island biotas are
not in equilibrium due to
human impacts.
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Theory Into Practice: Problems and
Prospects
Mark V. Lomolino, Ph.D.
Island community
structure is dynamic over
time but not necessarily
represented by a balancebetween immigration and
extinction.
The hierarchical model
incorporates feedback
processes such as interspecificinteraction and offers
explanations for such insular
phenomena as the distribution of
individual species, species-area-
isolation relationships, and even
patterns of assembly.