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

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
Areas where organisms are more vulnerable to extinctionPossess unusually high numbers of endemic species (those that are found only in that place)Generally near the tropicsGenerally 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 environmentExploit speciesIntroduce alien speciesPollute 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 agoWhen humans became farmers 10 000 years ago
Types of biodiversity
Genetic- the range of genetic material present in a species or a populationSpecies- the number of species in a given habitatHabitat- the number of different habitats per unit area
Species are formed through gradual change over timePhysical 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 hazardsloss of habitatfragmentation of habitatpollutionoverexploitationintroducing non-native (exotic species)spread of diseasemodern agricultural practices
What makes a species prone to extinction?
narrow geographical rangesmall population size of reclining numberslow population densities and large territoriesfew populations of the speciesa large bodylow reproductive potentialseasonal migrantspoor dispersersspecialized feeders or niche requirementshunted for food or sportminimum 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, China900 000 hectares of national reservesHome for giant pandas, red pandas, snow leopards1600 pandas, 6000 plant speciesActions taken:Human populations moved out of the reserveTightened laws on gun useEcotourism has assisted in funding the reserveConcerns:Giant pandas have a specialised diet of just bamboo, which limits their habitat
How does CITES workWhat are its strengths and weaknesses
CITES – the convention of international trade in endangered species of fauna and floraSpecies are ranked according to how threatened they are by international tradeAppendix I – species cannot be traded internationallyAppendix II – species can be traded internationally but with strict regulationsAppendix 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