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Chapter 38
Conservation Biology
PowerPoint Lectures
Campbell Biology: Concepts & Connections, Eighth Edition
REECE • TAYLOR • SIMON • DICKEY • HOGAN
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Lecture by Edward J. Zalisko
Figure 38.0-2
Chapter 38: Big Ideas
The Loss of Biodiversity
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THE LOSS OF
BIODIVERSITY
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38.1 Loss of biodiversity includes the loss of
ecosystems, species, and genes
• Biodiversity encompasses three levels:
1. ecosystem diversity,
2. species diversity, and
As natural ecosystems are lost, so are
3. genetic diversity.
essential services, including the
productivity of natural environments
for human food supplies and the
purification of water used by cities.
© 2015 Pearson Education, Inc.
38.1 Loss of biodiversity includes the loss of
ecosystems, species, and genes
• When ecosystems are lost, the populations that
make up their biological communities are also lost.
• The loss of just one species can negatively affect
the species richness of an ecosystem.
• Extirpation is the loss of a single population of a
species.
• Extinction is the irreversible loss of all populations
of a species.
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Percentage of species assessed
Figure 38.1b
100%
80%
Key
Lowest risk
of extinction
Near
threatened
Threatened
(high risk of
extinction)
Extinct or
extinct
in the wild
60%
40%
20%
0%
Mammals
Birds
Amphibians Reptiles Total animals
(N = 4,667) (N = 10,004) (N = 4,750) (N = 1,882) (N = 40,307)
Data from International Union for Conservation of Nature and Natural Resources (2012).
© 2015 Pearson Education, Inc.
38.1 Loss of biodiversity includes the loss of
ecosystems, species, and genes
• The genetic diversity within and between
populations of a species
• is the raw material that makes an adaptation to the
environment possible and
• a way to protect against future environmental
changes.
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38.1 Loss of biodiversity includes the loss of
ecosystems, species, and genes
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38.2 CONNECTION: Habitat loss, invasive species,
overharvesting, pollution, and climate change are major
threats to biodiversity
• Human alteration of habitats poses the single
greatest threat to biodiversity.
• Habitation alteration is caused by
•
•
•
•
•
•
agriculture,
urban development,
forestry,
mining,
environmental pollution, and
deforestation.
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38.2 CONNECTION: Habitat loss, invasive species,
overharvesting, pollution, and climate change are major
threats to biodiversity
• Invasive species rank second behind habitat
destruction as a threat to biodiversity.
• Invasive species
• compete with native species,
• prey on native species, and
• parasitize native species.
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38.2 CONNECTION: Habitat loss, invasive
species, overharvesting, pollution, and climate
change are major threats to biodiversity
• Overexploitation is the third major threat to
biodiversity. Overharvesting has
• threatened rare trees,
• reduced populations of tigers, Galápagos tortoises,
whales, and rhinoceroses, and
• depleted wild populations of game fish.
• In parts of Africa, Asia, and South America, wild
animals are heavily hunted for food.
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38.2 CONNECTION: Habitat loss, invasive species,
overharvesting, pollution, and climate change are major
threats to biodiversity
• Human activities produce pollutants that may affect
ecosystems far from their source.
• The water cycle transfers pollutants from terrestrial to
aquatic ecosystems hundreds of miles away.
• The release of chemicals into the atmosphere promote
the thinning of the ozone layer.
• Some pollutants contaminate
local areas.
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38.2 CONNECTION: Habitat loss, invasive species, overharvesting,
pollution, and climate change are major threats to biodiversity
• Biological magnification concentrates industrial
wastes and pesticides as they pass through the
food chain.
Top-level predators are
usually the organisms
most severely damaged
by toxic compounds in
the environment.
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