Download Organismal Biology/55A2-BiodiversityCrisis

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Habitat conservation wikipedia, lookup

Island restoration wikipedia, lookup

Extinction wikipedia, lookup

Transcript
CHAPTER 55
CONSERVATION BIOLOGY
Section A2: The Biodiversity Crisis (continued)
3. The four major threats to biodiversity are habitat destruction, introduced
species, overexploitation, and food chain disruptions
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
3. The four major threats to biodiversity are
habitat destruction, introduced species,
overexploitation and food chain disruption
• Habitat destruction.
• Human alteration of habitat is the single greatest
cause of habitat destruction.
• The IUCN states that destruction of physical habitat is
responsible for the 73% of species designated extinct,
endangered, vulnerable, or rare.
• About 93% of the world’s coral reefs have been
damaged by humans.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• Habitat destruction
has also caused
fragmentation of
many natural
landscapes.
Fig. 55.5
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• This can also lead to species loss.
Fig. 55.6
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• Introduced species.
• Introduced species are those that humans move from
native locations to new geographic regions.
• The Nile perch was
introduced into Lake
Victoria as a food fish,
but led to the extinction
of several native species.
Fig. 57.7a
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• There are many
examples of how
exotic species
have disrupted
ecosystems.
Fig. 57.7
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• Overexploitation.
• This refers to the human harvesting of wild plants
and animals at rates that exceed the ability of
those populations to rebound.
• The great auk was overhunted and became extinct.
Fig. 55.8
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• The African elephant has been overhunted and
the populations have declined dramatically.
• The bluefin tuna is another example of an overharvested species.
Fig. 55.9
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings
• Disruption of food chains.
• The extinction of one species can doom its
predators, but only if the predator feeds
exclusively on this prey.
• Much of the evidence for secondary extinctions of
larger organisms due to loss of prey is
circumstantial.
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings