Download Biodiversity - Mrs. McCrum Brooklin High School

Lesson 8 – Biodiversity
Our World Ontario
Biodiversity
• Biodiversity is the number of different
species living in a given area or ecosystem
• Approximately 1.5 million species have been
identified and studied
• Biologists estimate that there are between 5
and 50 million species on Earth
• Greater biodiversity exists in ecosystems near
the equator than in those near the poles
• Higher temperatures and greater amounts of
rainfall contribute to high biodiversity
Benefits of Biodiversity
• Ecosystems with high rates of biodiversity are
better able to remain healthy and stable when
disturbed
• The more diverse, the better able to withstand
diseases, droughts, loss of a species, or arrival
of new species
• Ecosystems with less diversity are more fragile
Protecting Biodiversity
• Human actions such as pollution, habitat
destruction, and the introduction of new
species can harm ecosystems
• The best way to protect biodiversity is to
limit these disturbances
• Protecting biodiversity keeps ecosystems
healthy
Biodiversity under Attack!
• There is greater threat to biodiversity in
areas that are heavily populated by humans
such as southern Ontario
• More natural ecosystems are cleared for
farming, housing, or road construction
• More pollution is created, which can damage
ecosystems and the organisms that live in
them
Species at Risk
• The greatest threat to biodiversity is that a
species can become extinct
• An extinct species no longer exists on Earth
• The Committee on the Status of Endangered
Wildlife in Canada (COSEWIC) monitors
species and separates them into four
categories:
Species at Risk
• Special Concern – may become threatened or
endangered because of various factors
– E.g. Polar bear, great blue heron, Atlantic cod
Species at Risk
• Threatened – likely to become endangered if
no action is taken
– E.g. Humpback whale, wood bison, Kentucky coffeetree
Species at Risk
• Endangered – in immediate danger of
becoming extirpated or extinct
– E.g. Barn owl, swift fox, northern cricket frog
Species at Risk
• Extirpated – no longer exists in the wild in a
specific area
– E.g. Paddlefish, grey whale
Species at Risk
• Extinct – no longer exists on Earth
– E.g. Great Auk, passenger pigeon, sea mink
Extinction
• Extinction is a process that may result from
natural catastrophes or gradual changes
• Asteroid impacts, volcanic eruptions, or
natural climate changes can wipe out entire
species, but they are rare
• The greatest threat to today’s species is
human activity
• Of 700 known vertebrates to have become
extinct in the last 400 years, 12 had lived in
Canada
Reasons to Protect Biodiversity
• Ensure ecosystem stability and sustain all life forms
• Provide natural processes to produce oxygen,
carbon dioxide, and nitrogen that protect our planet
• Help species adapt to changes in their environment
• Provide raw materials for food, clothing, medicine
• Enhance our quality of life by adding variety to our
surroundings
• Help shape our culture and inspire poets, painters,
and writers