1. Mass Extinction & Biodiversity
Higher Biology
Mass Extinction & Biodiversity
Mr G R Davidson

2. Extinction Extinction is the demise of a species.
They are usually replaced by another species better adapted to the environment.
If many species die out around the same time, this is known as a mass extinction.
Monday, 31 December 2018
G R Davidson

3. Extinction
Mass extinctions were usually caused by significant changes in the planet such as climate change.
Mass extinctions leave niches unfilled allowing the organisms which survive to fill these niches.
This results in new species being formed by speciation.
Monday, 31 December 2018
G R Davidson

4. Extinction Rates
Extinction rate is the number of species becoming extinct over a given period of time.
These rates are extremely difficult to estimate accurately and so are approximations.
Monday, 31 December 2018
G R Davidson

5. Extinction of Megafauna
Megafauna usually applies to animals greater than 44kg (or larger than humans).
Examples of megafauna extinction include the woolly mammoth and giant bison.
Extinction of megafauna is brought about by humans.
Monday, 31 December 2018
G R Davidson

6. Extinction of Megafauna
As humans try to cope with the ever rising population they damage more and more natural resources, e.g. chopping down forests for land, building dams and flooding huge areas, etc..
This is resulting in a much higher species extinction rate than normal.
Monday, 31 December 2018
G R Davidson

7. Measuring Biodiversity
Biodiversity is defined as the total variation existing among all organisms on Earth.
Biodiversity measurements can provide important information for biologists and can help determine which areas and organisms to support to maintain this biodiversity.
Monday, 31 December 2018
G R Davidson

8. Measuring Biodiversity
It is important that we retain a rich biodiversity to allow us to maintain resources which may be useful in future.
Biodiversity can be measured in three ways:
Species diversity
Genetic diversity
Ecosystem diversity
Monday, 31 December 2018
G R Davidson

9. Species Diversity
This is a measure of the number of different species and the abundance of each species within an ecosystem.
An ecosystem with a dominant species will have a lower diversity than an ecosystem without a dominant species.
Monday, 31 December 2018
G R Davidson

10. Genetic Diversity
Genetic diversity is the number and frequency of alleles within a population.
If particular populations die off then alleles are lost and genetic diversity is lowered.
This may limit the ability of the species to adapt to their ever changing environment.
Monday, 31 December 2018
G R Davidson

11. Ecosystem Diversity
This is the number of distinct ecosystems within a defined area.
The more ecosystems there are, the greater the biodiversity will be due to the greater number of natural resources available.
Monday, 31 December 2018
G R Davidson