3.7 Mass Extinction and Biodiversity Flashcards
Define ‘Biodiversity’
Biodiversity is the total variation that exists amongst all living things
What is ‘Extinction’ and when does it occur?
Extinction is the complete demise of a group of organisms. It occurs when the organisms fail to adapt to their environment.
What suggests there have been multiple mass extinctions in the earth’s history?
Fossil Evidence
What is ‘Mass Extinction’
Mass Extinction is a period of time in Earth’s history when an abnormally large number of species die out within a short time frame
Following a mass extinction how is biodiversity regained?
Adaptive Radiation of Survivors
Explain what adaptive radiation is?
Adaptive Radiation is where the survivors of an extinction become suited to their environment and are able to successfully reproduce and recolonise
What are mass extinctions usually a result of?
Change to global climate
What is ‘Extinction Rate’?
Extinction Rate is the number of species that become extinct in a given area per unit time
Why is extinction rate and estimation of extinction dates not always accurate?
Fossil evidence is biased, some creatures(vertebrate for example) fossile better.
What coincided with the arrival of homo sapiens?
Extinction of the Megafauna
What are ‘Megafauna’
Large or giant animals
Why is it important to maintain biodiversity?
- Access to raw materials
- Access to fuels
- Aesthetics
- Access to food
- Maintain the genetic diversity
What are the three measurable components of biodiversity?
Genetic Diversity
Species Diversity
Ecosystem Diversity
Define <em>‘Genetic Diversity’</em>
Genetic diversity comprises the genetic variation shown by the NUMBER AND FREQUENCY OF ALLELES IN A POPULATION
What is a measure of genetic diversity?
Number and Frequency of alleles in a population
Define <em>‘Species Diversity’</em>
Species diversity comprises the species richness and the relative abundance of the ecosystem
What is ‘species richness’?
The number of species present in an ecosystem
What is ‘relative abundance’?
The proportion of each species in an ecosystem
Define <em>‘Ecosystem Diversity’</em>
The number of distinct ecosystems in an area
What is Island Biogeography?
Study of the factors that affect the distribution and diversity of species on island
What are the two types of island and describe the differences between them?
True island - a land mass surrounded by water
Habitat Island - area surrounded by an unlike ecosystem
How does area and isolation of ecosystem affect its species diversity?
The SMALLER and MORE ISOLATED an ecosystem, the <strong> LOWER </strong> the species diversity
What is the effect of a dominant species on species diversity?
An ecosystem with a dominant species will have a LOWER species diversity than an ecosystem with the same species richness
