4 – biodiversity

Open systems
Exchange matter and energy
Closed systems
Exchange only energy
Isolated systems
Don’t exchange anything and are theoretical
1st law of thermodynamics
Matter can be neither created nor destroyed
2nd law of thermodynamics
Over time the entropy of a closed system increases
Background extinction rate
The natural extinction rate of organisms
E.O. Wilson
a biologist at Harvard, thinks that the current rate of extinction is 1000 times the background rate and is caused by human activities
Hotspots
Areas where organisms are more vulnerable to extinction
Possess unusually high numbers of endemic species (those that are found only in that place)
Generally near the tropics
Generally have high densities of humans nearby
How many extinctions have there been in the past? What is the current one called
5, we are currently undergoing the 6th one, called the Holocene extinction event
How have humans contributed to the 6th mass extinction?
Transform the environment
Exploit species
Introduce alien species
Pollute the environment
A report that measures trends in Earth’s biodiversity
Living Planet Report
Two phases to the sixth mass extinction
When humans spread over the earth 100 000 years ago
When humans became farmers 10 000 years ago
Types of biodiversity
Genetic- the range of genetic material present in a species or a population
Species- the number of species in a given habitat
Habitat- the number of different habitats per unit area
Speciation
Species are formed through gradual change over time
Physical separation of a species in two can lead to divergence (cannot interbreed, different environments demand different characteristics)
Example: llamas (south america) and camels (africa, asia)
Factors leading to a loss of biodiversity
Natural hazards
loss of habitat
fragmentation of habitat
pollution
overexploitation
introducing non-native (exotic species)
spread of disease
modern agricultural practices
What makes a species prone to extinction?
narrow geographical range
small population size of reclining numbers
low population densities and large territories
few populations of the species
a large body
low reproductive potential
seasonal migrants
poor dispersers
specialized feeders or niche requirements
hunted for food or sport
minimum viable population size: that is needed for a species to survive in the wild is a figure that scientists and conservationists consider
Example of a recovered species
Australian saltwater crocodile
>listed as protected species
>overexploited through illegal hunting
>restored through ranching
Example of an extinct species
Dodo
>bird endemic to Mauritius
>hunted for meat and later for sport
>newly introduced alien predator species
>destruction of habitat
Example of an endangered species
Rafflesia
>tropical plant in South-East Asia
>vulnerable because needs specific conditions to survive
>habitat is destroyed by deforestation
>rafflesia sanctuaries
What factors are used to determine whether an organism is registered in the Red Book?
>population size + population trend
>geographic range size
>numbers of mature organisms
>quality and size of habitat
>likelihood of extinction
The importance of biodiversity
>food
>useful genes aren’t lost (such as genes of organisms immune to certain diseases)
>natural products (timber, medicine)
>recreation
>keystone species
>stability
>indicator species
>preserving indigenous communities
Evaluate the success of a named protected area
—Sichuan giant panda sanctuary—
Located in Sichuan, China
900 000 hectares of national reserves
Home for giant pandas, red pandas, snow leopards
1600 pandas, 6000 plant species

Actions taken:
Human populations moved out of the reserve
Tightened laws on gun use
Ecotourism has assisted in funding the reserve

Concerns:
Giant pandas have a specialised diet of just bamboo, which limits their habitat

How does CITES work
What are its strengths and weaknesses
CITES – the convention of international trade in endangered species of fauna and flora

Species are ranked according to how threatened they are by international trade
Appendix I – species cannot be traded internationally
Appendix II – species can be traded internationally but with strict regulations
Appendix III – species included at the request of a country, which then needs the cooperation of other countries to help prevent the illegal exploitation

+ species are protected from extinction
– simply protecting the species isn’t as efficient as protecting their habitat

Strengths and weaknesses of captive breeding, reintroduction to habitat, zoos
+ prevents the extinction of species
+ reintroduction programs provide jobs and promote education
+ zoos are the most viable option if the habitat of a species is destroyed

– it’s impossible to keep every species captive
– reintroduction programs are expensive and difficult
– zoos keep animals in close confinement
– zoos raise money for further research