Download Loss of Biodiversity

SC.912.L.17.8
Earth's Biodiversity
Earth’s biodiversity
Biodiversity – the diversity of life on Earth
– variety at all levels of biological organization
Components of biodiversity:
• Genetic diversity – genetic variation within populations
or species
• Species diversity – numbers of species within an area
• Diversity among higher taxa – variation between
genera,
families, orders, etc.
• Ecosystem diversity – variation among ecosystems,
communities, landscapes
Why is biodiversity important?
Economic value – resources, including food
– medicines and other helpful chemicals
– genes for better crops
– “opportunity cost”
Utilitarian value – prevent erosion
– purify water
– recycle CO2
– regulate climate
– recycle nutrients through decomposition
– collectively, “ecosystem services”
Psychological value – direct or indirect enjoyment of nature
Intrinsic value – independent of humans
What is the “biodiversity crisis”?
Humans are causing extinctions at a tremendous rate.
• ~100 times faster than expected without human activity
• parallels or exceeds previous mass extinction events
Why is the loss of biodiversity a crisis?
• economic value of biodiversity lost or threatened
• “ecological services” lost or threatened
• ecosystems more vulnerable to further degradation
What are the biggest threats to
biodiversity?
habitat destruction and
fragmentation
pollution
 introduced species
overexploitation
Habitat Destruction &
Fragmentation
• When land is developed, natural habitats may be
destroyed
• Habitat fragmentation: development splits an
ecosystem into pieces
• Result is that pieces of the habitat become islands;
allowing fewer species to live there
• The smaller the population=more vulnerable to further
disturbance or climate change
Overexploitation
• Throughout history, humans have pushed some
animals into extinction by hunting them for food or
other products
• Hunting still threatens rare animals in parts of Africa,
South America, and Southeast Asia
• For meat, fur, or hides
• Some believe parts have medicinal properties
Pollution
• DDT
• Sewage and garbage
• Runoff
All of these get into ground water supplies and can be
consumed by plants, and then animals
Introduced species
Invasive species: non-native plants and animals
introduced to an area, reproduce rapidly, and outcompete the local organism