Unit 3 VCEEnvironmental Science Area of Study 2: Biodiversity Britt Gow, 2012
Definition:• Biodiversity (biological diversity) is the total sum of all the living organisms that exist on our earth.• This living wealth is the product of hundreds of millions of years of evolutionary history.• “The variability among living organisms from all sources including terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are a part; this includes diversity within species, between species and of ecosystems” International Convention on Biological Diversity.
Biological Diversity• Todays biodiversity is the result of billions of years of evolution, natural processes, and in more recent years, human activity. Before Homo sapiens, the Earths biodiversity was much greater than it is today. Human activity has had a tremendous impact on biodiversity due to use of Earths resources and exponential population growth.• The total number of species on Earth today is estimated to be around 10 million different species, but could be as low as 2 or as high as 100 million. New species are discovered often, and many that have been discovered have not yet been classified. The richest sources of biodiversity on Earth are found in tropical rainforests and the ocean.
Three Levels:• Genetic Diversity – genes on chromosomes determine the specific characteristics (physical, emotional) of individual organisms. Diversity of genes within a species and processes such as mutations, gene exchanges, and genome dynamics that occur at the DNA level and generate evolution.• Species Diversity – variety of different types (species) of organisms• Ecosystem Diversity – variety of different ecosystems from marine to desert to tropical rainforest to temperate Eucalypt forest to wetlands etc.
Genetic Diversity• The reason captive breeding programs need to introduce new individuals from wild populations.• a species with high genetic diversity will tend to produce a wider variety of offspring, where some of them may become the most fit variants.• In contrast, a species that has little or no genetic diversity will produce offspring that are genetically alike and therefore will likely be susceptible to diseases or problems similar to those of their parent.• Hence, little or lack of genetic diversity reduces biological fitness and increases the chances of species extinction.• Larger populations have greater genetic diversity and are therefore less vulnerable to change and more adaptable and sustainable.
Geneticists are working to improve our food crops by making them less vulnerable to disease, drought and crop failure. Humans need to provide food for a growing population by increasing productivity.Genetic studies show thatthe cheetah has a very lowgenetic diversity, indicatingthat the population hascrashed to about 200individuals at some time inthe past. They arevulnerable to extinction forthis reason.
Species Diversity can be measured by counting the number of organisms of each species.“The existence of a widerange of different types oforganisms in a given placeat a given time. Thediversity of plant andanimal life in a particularhabitat.”
Ecosystem Diversity• Variety of habitats, living communities and ecological processes in the living world.• Includes alpine, dry-schlerophyll, mallee, tropical rainforest, savannah (grassland), freshwater aquatic, temperate marine, Antarctic etc, each with it’s own characteristic species and food webs.• Often preserved by National parks and reserves.
Australian Biodiversity• Australia has an incredibly diverse range of life due to it’s isolation from other continents.• Australia is recognised as one of the most mega-diverse countries on the planet, with many endemic species, such as our iconic marsupials and monotremes, banksias, eucalypts and grevilleas.
Why Conserve Biodiversity?• Ecosystem services• Biological resources• Social benefits
Products Services Social BenefitsPlants (trees,grasses, palms,herbs)FungiMicro-organismsInvertebratesVertebrates
Conservation of Biodiversity• Genetic – variety of breeding pairs in captive programs, different groups in separate locations• Population – conserving a particular population within a precise geographic area• Species – preserving different species of organisms (management plans)• Ecosystem – National parks and conservation reserves
Assessment of Biodiversity• Species richness (no. of different species)• Species diversity (abundance of each different species)• Simpson’s Index• Shannon-Weiner Diversity Index
Threats to Biodiversity - CHIPPO• Climate Change• Habitat destruction• Introduced animals• Pollution• Pest plants• Over-harvesting
IUCN Conservation Categories• Extinct• Extinct in the wild• Critically endangered• Endangered• Vulnerable• Conservation dependent• Data deficient• Low risk• Not evaluated
Strategies for protecting Biodiversity• Action plans• Captive breeding programs• Conservation reserves• Revegetation and habitat restoration• Feral species control• Ecotourism• Education