Download Conservation Biology and Restoration Ecology

Conservation
Biology and
Restoration Ecology
Chapter 55
• Three Levels of
Biodiversity
Genetic Diversity
• Genetic differences within a
population
• Genetic variations between
populations
Species Diversity
• Is the variety of species in an
ecosystem or throughout the
biosphere
Conservation biologists are
concerned about species
loss
– Because of a number of alarming
statistics regarding extinction and
biodiversity
Ecosystem Diversity
• Variety of ecosystems in the biosphere
• The local extinction of one species can
have a negative impact on the overall
species richness of the community
• Human activity is affecting ecosystem
diversity
• Biophilia--our sense of connection to
nature and other forms of life
Ecosystem services
• Ecosystem services encompass all
the processes
– Through which natural ecosystems and
the species they contain help sustain
human life on Earth
Includes…
– Purification of air and water
– Detoxification and decomposition of
wastes
– Cycling of nutrients
– Moderation of weather extremes
– And many others
Major threats to biodiversity
• Most species loss can be traced to
four major threats
– Habitat destruction
– Introduced species
– Overexploitation
– Disruption of “interaction networks”
Habitat Destruction
• Human alteration of habitat
– Is the single greatest threat to
biodiversity throughout the biosphere
• Massive destruction of habitat
– Has been brought about by many
types of human activity
Introduced Species
• Those that humans move, either
intentionally or accidentally, from
the species’ native locations to new
geographic regions
Introduced species…
• That gain foothold usually disrupt
their adopted community, often by
preying on native organisms or
outcompeting them for resources
Overexploitation
• Human harvesting of wild plants or
animals at rates exceeding the
ability of population of those species
rebound
Figure 55.7
Disruption of Interaction
Networks
• The extinction of one species can
doom others, particularly when the
extinction involves a keystone
species
Concept 55.2: Population conservation focuses
on population size, genetic diversity, and critical
habitat
Two approaches:
•Conservation biologists who adopt the smallpopulation approach
–Study the processes that can cause very small
populations finally to become extinct
Extinction Vortex
• Small pops. Prone to
This positive feedback
Loop that draw pop
Down an extinction
vortex
Small
population
Inbreeding
Lower
reproduction
Higher
mortality
Reduction in
individual
fitness and
population
adaptability
Figure 55.9
Genetic
drift
Smaller
population
Loss of
genetic
variability
• The key factor driving the extinction
vortex
– Is the loss of the genetic variation
necessary to enable evolutionary
responses to environmental change
• The minimum viable population
(MVP)
– Is the minimum population size at which
a species is able to sustain its numbers
and survive
• A population viability analysis (PVA)
– Predicts a population’s chances for
survival over a particular time
– Factors in the MVP of a population
Declining Population
Approach
• The declining-population approach
– Focuses on threatened and
endangered populations that show a
downward trend, regardless of
population size
– Emphasizes the environmental factors
that caused a population to decline in
the first place
• The declining-population approach
– Requires that population declines be
evaluated on a case-by-case basis
– Involves a step-by-step proactive
conservation strategy
• Landscape and regional
conservation aim to sustain entire
biotas
Landscape Structure and
Biodiversity
• The structure of a landscape can
strongly influence biodiversity
• The boundaries, or edges, between
ecosystems
– Are defining features of landscapes
(a) Natural edges. Grasslands give way to forst ecosystems in
Yellowstone National Park.
Figure 55.14a, b
(b) Edges created by human activity. Pronounced edges (roads)
surround clear-cuts in this photograph of a heavily logged rain
forest in Malaysia.
• As habitat fragmentation increases
and edges become more extensive,
biodiversity tends to decrease
• A movement corridor
– Is a narrow strip of quality habitat
connecting otherwise isolated patches
– Can promote dispersal and help sustain
populations
Biodiversity Hot Spots
• A biodiversity hot spot is a relatively
small area
– With an exceptional concentration of
endemic species and a large number
of endangered and threatened
Terrestrial
biodiversity
species
hot spots
Equator
Figure 55.17
• Nature reserves are biodiversity
islands
– In a sea of habitat degraded to
varying degrees by human activity
• The zoned reserve model recognizes
that conservation efforts
– Often involve working in landscapes
that are largely human dominated
• Concept 55.4: Restoration ecology
attempts to restore degraded
ecosystems to a more natural state
• Bioremediation
– Is the use of living organisms to detoxify
ecosystems
• Biological augmentation
– Uses organisms to add essential
materials to a degraded ecosystem
• The newness and complexity of
restoration ecology
– Require scientists to consider
alternative solutions and adjust
approaches based on experience
• Concept 55.5: Sustainable
development seeks to improve the
human condition while conserving
biodiversity
Sustainable Biosphere
Initiative
• Acquire the ecological information
needed for the development,
management, and conservation
Biophilia and the Future of
the Biosphere
• Our innate sense of connection to
nature may eventually motivate a
realignment of our environmental
priorities