VI' Biodiversity Crisis

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VI. Biodiversity Crisis

• Three components of biodiversity
• a) diversity of ecosystem
• b) variety of the species in a community
• c) genetic variation within each species
• -any change in these components greatly affects
  the biodiversity of that community

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B. Loss of Species -1.5 million species
identified -this is 10 of all species -11 of
bird species endangered -970 tree species
critically endangered -20 freshwater fish
threatened Hundred Heartbeat Club species than
number less than 100
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C. 3 Causes of the Biodiversity Crisis

• Habitat Destruction-humans, single greatest
  threat
• Introduced Species - human introduction replaces
  native species. E.g. starling, pigeons, sparrows
• Overexploitation - commercial harvest or sport
  hunting. E.g. whales, bison, elephants, dolphins,
  numerous fish

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D. Why Biodiversity matters
-25 of all prescriptions come from
plants -Hodgkins disease - rosy
periwinkle -human survival depends on the
biosphere -we may discover new food medicine
sources,
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VII. Conservation Biology

• A goal-oriented science that seeks to counter the
  loss of biodiversity.
• Biodiversity Hot Spots-a relatively small area
  w/an exceptional concentration of species
• -many species are endemic species - they are
  found nowhere else
• -rainforests and chaparral (California)
• -less than 1.5 of earths land but 1/3 of all
  species

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• B. Conservation at the Population species
  levels
• Endangered species - in danger of extinction
• Threatened species - likely to become endangered
• Population fragmentation -humans have caused
  patchy habitats isolated species
• -decrease in size of population gene flow

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2) Source habitat - subpopulations reproduction
exceeds death rate 3) Sink habitat - death rate
exceeds reproduction-increasing C. Species vs.
culture saving owls, fish, wolves, bears vs.
timber mining industries and ranchers.
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D. Conservation at ecosystem level

• Landscape ecology - applications of ecological
  principles to the study of land-use patterns.
• Edges corridors - the edge of an ecosystem may
  have its own community. May be positive or
  negative. E.g. deer live in edge come out to
  feed. A forest has more trees blown down on the
  edge
• movement corridor - narrow strip connecting
  otherwise isolated patches. E.g. streams
• -positive-migration, help sustain a species
• -Negative - spread of disease

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2. Zoned Reserves - extensive land undisturbed by
humans E. Sustainable Development - balance of
human needs and the biosphere
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