Lecture 17 Flashcards
Meaning of conservation
- Stewardship of the natural world
- Sustainably use resources that exist in the natural world (resource conservation)
The natural world is defined by…
biodiversity at the genetic species richness and landscape scale
Conservation
- How to mitigate long term effects of biodiversity crisis.
- We are destroying biodiversity at 3 levels at a catastrophic rate
- We are the agents of this destruction
Understanding the key pressure points within biodiversity process, we can best mitigate these effects
Extinction
Worse case scenario for biodiversity
- Extinctions have always been a natural part of life
- most organisms who have existed are extinct
- Periods of mass extinction really affect the way life on earth is
What are the 6 mass extinctions
- 440mya: the Ordovician-Silurian extinction
- Global cooling
- 1/4 of marine families go extinct - 370 mya: Devonian- Carboniferous exstinction
- Volcanic eruption- block out the sun
- cold 20% die - 245 mya: Permian mass extinction
- 54% of families and 96% of species
-Result of volcanic activities
- Sulphur in air and water cold - 210 mya: Triassic Jurassic exstinction
- 65mya: Cretaceous tertiary extinction
- Most recent
- 76% of species die
- Something hit earth
- spewed debris into atmosphere
- Herbivores and plants in trouble
- earth was dark for 3 years
All predates humans
3 and 5 are important
Extinction
Followed by periods of adaptive radiation as newly evolved organisms occupy now vacant niches
- new organisms move in and adapt to
ex. kt extinction organisms who could survive in dark once they survive they adaptively radiate
- Explosion of mammals and birds
- organisms spreading new behaviours to occupy new niches
Burgess Shale
Was bottom of ocean
lots of extinct organisms
Extinction today
- everything we know about extinction is from focil records
- All observable extinctions have been anthropogenic
- We’ve observed exstrepations
Holocene extinction
Current area
anthropogenic area
period since last glaciers retreated
this happened 11 thousand years ago (must know)
isn’t naturally occurring
- It’s the activities of the Homo sapiens dominating earth
- diverse anthropogenic stressors drive current biodiversity crisis
- Over harvesting climate change invasion of aliens
- Pollution global catastrophe
= small fragmented pop
- Demographic instability
- inbreeding depression
= extinction
How many years ago did glaciers retreat?
11 thousand yers ago
What are the 3 main elements of the Holocene extinction
- Species extinction are occurring at abnormally high rates
- # of endangered species rising quickly
- Natural communities are being diminished
(richness and evenness going down)
E.O Wilson
predicted1/2 of known species will be extinct
Species at risks
- No group of organisms or region on earth is immune
Holocene extinction event
Pleistocene epoch lasted 3 mya
The Holocene begain 10 000 years ago when glaciers retreated
- The Pleistocene allowed migration-water was ice could walk across ocean
- people colonized alaska and the rest of americas > 12000
- As humans moved in large organisms started to go extinct
- wherever humans move, we drive large animals to extinction
Island vulnerability
Organisms that live on islands and are not found in other places are particularly sensitive
- Endemic species instead of extirpation they go extinct
- dodos. Big flightless bird, no native predators
- hunted for food
Great Auks: historically eaten by Canadian’s first people
- large flightless quickly overharvested
Resent extinction
- Passenger pigeons
3-5 billion - migrate together in giant flocks
- pigeons were hunted for food
- Michigan’s harvest was a billion passenger pigeons in one year
- 1914 died
- Ivory billed woodpecker
- Giant
- Lives in swamp
- eat gubs
- Big mature forest were quickly cut down
- Final ivory billed woodpeckers were hunted by ornothonalagists
- last seen in 1944
- Extinction due to habitat loss
Cause of anthropogenic extinction
Over harvesting (passenger pigon, dodo)
Habitat destruction (ivory billed woodpeckers)
Introduction to alien species
Where is most biodiversity?
Tropical forests have the most biodiversity
- Must be protected
- rapidly being reduced to export products to us
slash and burn habitat distruction
