Jeanne Lee
NOTE: I am not responsible for any incorrect information. This set of notes was from
Summer 2010 so I donʼt even really know exactly whatʼs on here. Have fun reading!
AP Biology Ch. 56 Notes
Overview: Striking Gold
• conservation biology: integrates ecology, physiology, molecular biology, genetics,
and evolutionary biology to conserve biological diversity
• restoration ecology: applies ecological principles to return disturbed ecosystems
back to natural state
56.1 Human activities threaten Earthʼs biodiversity
• Three Levels of Biodiversity
• Genetic Diversity
• individual genetic variation within a population
• genetic variation between populations associated w/ adaptations to local
conditions
• allows scientists to breed good traits into plants that are becoming extinct
Species
Diversity
•
• variety of species in ecosystem or throughout biosphere
• endangered species: one that is “in danger of extinction throughout all or
significant portion of its range
• threatened species: those that are considered likely to become endangered
species in the future
Ecosystem
Diversity
•
• variety of a biosphereʼs ecosystems
• community interactions are in network
• local extinction of one species can have negative impact on overall species
richness of community
• Biodiversity and Human Welfare
• biophilia: our sense of connection to nature and other forms of life
• Benefit of Species and Genetic Diversity
• many threatened species could provide crops, fibers, and medicines for humans
• rosy periwinkle grown in Madagascar - contains alkaloids that inhibit cancer cell
growth
• led to treatments for Hodgkinʼs disease and childhood leukemia
• each loss of a species means loss of unique genes
Ecosystem
Services
•
• ecosystem services: the processes through which natural ecosystems help
sustain human life
• ecosystems purify air and water, detoxify and decompose wastes
• reduce impacts of extreme weather and flooding
• organisms in ecosystems pollinate crops, control pests, create and preserve soil
• Three Threats to Biodiversity
• Habitat Loss
• human alteration of habitats greatest threat to biodiversity
• brought about by agriculture, urban development, forestry, mining, pollution
• global warming altering habitats today as well
• when no habitat is available, species can become extinct
• 98% of tropical dry forests of central america and mexico have been cut down
• smaller populations in habitat fragments have higher probability of local
extinction
• freshwater habitats being lost
• result of dams, reservoirs, channel modification, etc.
• Introduced Species
• introduced species: non-native/exotic species
• species that humans move, intentionally or accidentally from speciesʼ native
locations to new geographic regions
• transplanted species may spread very rapidly through new region
• introduced species disrupt adopted community by preying on organisms or
outcompeting them for resources
• contribute to 40% of extinctions since 1750
• Overexploitation
• refers to human harvesting of wild organisms at rates exceeding ability of
populations of those species to rebound
• using too much
• species w/ restricted habitats vulnerable to overexploitation
• large organisms w/ low intrinsic reproductive rates like elephants, whales, and
rhinoceroses also vulnerable
56.2 Population conservation focuses on population size, genetic diversity, and critical
habitat
• two ways to approach conservation; small population approach and declining
population approach
• Small-Population Approach
• small populations especially vulnerable to overexploitation, habitat loss, and other
threats
• this approach allows biologists to study what causes extinctions once population
sizes have been severely reduced
• The Extinction Vortex
• small pop. prone to positive feedback loops of inbreeding and genetic drift
• causes extinction vortex: towards smaller and smaller population size
• key factors driving vortex
• loss of genetic variation necessary to enable evolutionary responses
• inbreeding reduces fitness b/c offspring more likely to be homozygous for
harmful recessive traits
• Case Study: The Greater Prairie Chicken and the Extinction Vortex
• greater prairie chicken common across western prairies
• land cultivation for agriculture fragmented population and abundance of species
was drastically reduced
• researchers expecting the extinction vortex brought in 200 some birds from
larger populations elsewhere
• population rebounded
• Minimum Viable Population Size
• how small does population have to be for it to be heading down extinction
vortex?
• minimum viable population (MVP): minimal population size at which species
able to sustain numbers and survive
Effective
Population Size
•
• total size of population misleading b/c only certain members of population breed
successfully and pass alleles on to offspring
• effective population size: based on breeding potential of population
• formula:
• Ne = effective pop. size
• Nf = number of females
• Nm = number of males ; both successfully breed
• Ne = (4NfNm) / (Nf + Nm)
• Ne always fraction of total population
• conservation programs attempt to sustain population sizes that include at least
minimum viable number of reproductively active individuals
• Declining-Population Approach
• focuses on threatened and endangered populations that show a downward trend
• approach emphasizes environmental factors that caused a population decline in
first place
• Steps for Analyses and Intervention
• requires that population declines be evaluated on case-by-case basis
• steps
• confirm that species is presently in decline or was formerly more widely
distributed or abundant
• study natural history of this and related species
• develop hypotheses for all possible causes of decline - list prediction
• test most likely hypothesis first
• apply results of diagnosis to manage threatened species
• Weighing Conflicting Demands
• conservation biology highlights relationship b/n science, technology, and society
• debate in U.S. Pacific Northwest - habitat preservation for northern spotted owl,
timber wolf, grizzly bear, and bull trout v. job opportunities in timber, mining, and
extraction industries
• need to consider ecological role of species b/c canʼt save every species have to
save ones most important for conserving biodiversity
56.3 Landscape and regional conservation aim to sustain entire biotas
• Landscape Structure and Biodiversity
• Fragmentation and Edges
• edges = boundaries between ecosystems
• edge has own set of physical conditions different than the ecosystems
• some organisms thrive in edge communities b/c get resources from both
ecosystems
• proliferation of edge species
• edges may be important sites of speciation
• communities in which edges arise from human alterations have reduced
biodiversity - large percentage of edge habitat will lead to edge-adapted
species
• Corridors That Connect Habitat Fragments
• movement corridor: narrow strip or series of small clumps of habitat
connecting otherwise isolated patches
• can be important in conserving biodiversity
• can promote dispersal and reduce inbreeding in declining populations
• corridors increase exchange of individuals
• important to species that migrate b/n habitats seasonally
• harmful effect: spread of disease
• Establishing Protected Areas
• Finding Biodiversity Hot Spots
• biodiversity hot spot: relatively small area with huge concentration of endemic
species and large number of endangered and threatened species
Philosophy
of Nature Reserves
•
• nature reserves: biodiversity islands in a sea of habitat degraded to varying
degrees by human activity
• philosophy: protected areas should be set aside to remain unchanged forever
• need to keep in mind disturbances that are necessary for biodiversity
• large, extensive reserves needed for large, far-ranging animals w/ low-density
populations
• however, smaller, unconnected reserved will slow spread of disease throughout
population
• Zoned Reserves
• zoned reserve: extensive region that includes areas undisturbed by humans
surrounded by areas thatʼve been changed by human activity and are used for
economic gain
• surrounding habitat serve as buffer zone against intrusion into undisturbed area
56.4 Restoration ecology attempts to restore degraded ecosystems to a more natural
state
• degraded habitats increasing in area b/c natural rate of recovery by successional
processes slower than rate of degradation by human activities
• soils become unproductive and are abandoned after being cleared for farming
• humans come in, use as desired, and leave land abandoned
• restoration ecology
• seeks to speed up recovery of degraded ecosystems
• assumptions: environmental damage partly reversible
• work to identify and manipulate processes that limit speed of recovery
• Bioremediation
• bioremediation: use of organisms to detoxify polluted ecosystems
• organisms: prokaryotes, fungi, or plants
• plants
• some plants adapted to soils containing heavy metals can accumulate high
concentrations of metals
• metals: zinc, nickel, lead, and cadmium
restoration
ecologists use these plants to revegetate sites polluted by mining and
•
other activities
• then harvest plant to remove metals from ecosystem
• prokaryotic species
• some bacterium: shewanella oneidensis can metabolize more than 10 elements
under aerobic and anaerobic conditions to generate energy
• converts uranium, chromium, and nitrogen to insoluble forms less likely to leach
• Biological Augmentation
• biological augmentation: uses organisms to add essential materials to a
degraded ecosystem
• need to determine what chemical nutrients have been removed from area that
limits rate of recovery
• plants that can live in nutrient-poor soils can speed up rate of successional
changes
Read pages 1262 to 1263 on famous restoration projects.
56.6 Sustainable development seeks to improve the human condition while conserving
biodiversity
• Sustainable Biosphere Initiative
• sustainable development: development that meets needs of people today w/o
limited ability of future generations to meed their needs
• sustainable biosphere initiative goal: acquire basic ecological info needed to
develop, manage, and conserve earthʼs resources as responsibly as possible
• The Future of the Biosphere
• biophilia: sense of connection to nature and other forms of life (by humans)
• attachment to nature and diversity of life