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CHAPTER 2: BIODIVERSITY CHANGE OVER TIME (ENVIRONMENTAL VARIATION (SHORT…
CHAPTER 2: BIODIVERSITY CHANGE OVER TIME
EVOLUTION
Theory of evolution via natural selection: supports gradual change in population characteristics over time i.e "survival of the fittest"
Gene pool evolves in population as genes with the higher chance of survival and reproducing in environment, increase.
Gives rise to biological diversity / Where over time, sub-populations of a species can evolve into separate species, w/ different characteristics favoured in their environments
EXTINCTION
= If changes in environment occur too quickly and population struggle to adapt. i.e the complete disappearance of a species or a local population / can be caused by a natural event
ENVIRONMENTAL VARIATION
POPULATION ISOLATION
: Result from environmental changes that may lead to local extinction of a species / May produce a sub-species that cannot interbreed
SHORT-TERM CHANGES
(e.g fire, volcanic eruptions)
Threaten survival of individual populations or ecosystems. Particularly those that are vulnerable (ecosystems or species that are endemic to a small locality)
MEDIUM-TERM CHANGES
El Nino-Southern Oscillation (ENSO): climatic cycle over 3-8 years, due to Australia's rainfall. / Changes in sea surface temperatures and average atmospheric pressure in and above the Pacific Ocean.
LONG-TERM CHANGES
CONTINENTAL DRIFT:
plate tectonics moving the Earth's continental plates
Result in formation of continents, mountain ranges, valleys over long periods of time --> providing environmental conditions for isolated populations to evolve into new species.
Regions found close to the equator have greater diversity of species than ecosystems found in temperate and arctic climates
AUSTRALIA'S BIODIVERSITY
OUR UNIQUE FLORA AND FAUNA
- Aus' endemic species formed as a result of its long periods of separation from other continents (Gondwana was the supercontinent)
A BIODIVERSITY HOTSPOT
- Areas where natural ecosystems + native species and communities in these ecosystems are well represented and remain largely as a whole.
Include many locally endemic species (species not found outside the hotspot)
STUDY DESIGN
: Biodiversity change over time
• the isolation of populations over short (volcanic eruptions or fire), medium (El Nino) and long (tectonic plate movement and evolution) time scales that can produce different species that are unable to interbreed, are endemic to a location, form a diversity hotspot, or become extinct, including explanation of why some ecosystems are more diverse than others.
• the impact of humans on the present rate of species extinction