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PowerPoint LecturesCampbell Biology: Concepts & Connections, Eighth EditionREECE • TAYLOR • SIMON • DICKEY • HOGAN

Chapter 38

Lecture by Edward J. Zalisko

Conservation Biology

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Figure 38.0-2

Chapter 38: Big Ideas

The Loss of Biodiversity

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THE LOSS OFBIODIVERSITY

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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, and3. genetic diversity. As natural ecosystems are lost, so are

essential services, including the productivity of natural environments

for human food supplies and the purification of water used by cities.

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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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Figure 38.1b

100%

80%

60%

40%

20%

0%

Perc

enta

ge o

f spe

cies

ass

esse

d

Mammals(N = 4,667)

Birds(N = 10,004)

Amphibians(N = 4,750)

Reptiles(N = 1,882)

Total animals(N = 40,307)

Data from International Union for Conservation of Nature and Natural Resources (2012).

KeyLowest riskof extinctionNearthreatenedThreatened(high risk ofextinction)Extinct orextinctin the wild

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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.