Key Area 7 & 8: Components & Threats to Biodiversity Flashcards
What is Biodiversity?
A measurement of the total variety of life in a particular area
The overall biodiversity of Earth can be estimated into what 3 components?
- Genetic Diversity
- Ecosystem Diversity
- Species Diversity
What is Genetic Diversity?
The number and frequency of all the alleles within a species
If one population of species dies out (local extinction) what happens?
The species will have lost some of it’s genetic diversity. This may limit the species’ ability to adapt to changing environmental conditions as less variation exists
What is Ecosystem Diversity?
The number of distinct ecosystems within a defined area
What is Species Diversity?
Species diversity is detemined by the species richness and relative abundance of species in an ecosystem.
What is Species Richness?
The number of different species in an ecosystem
What is Relative Abundance?
The proportion of each species in the ecosystem
What is a Dominant Species?
A species that has a high relative abundance in a community
What happens if a community does/doesn’t have a Dominant Species?
A community with a dominant species has a lower Species Diversity than one with the same Species Richness but no particularly Dominant Species
What are the 4 Threats to Biodiversity?
- Overexploitation
- Bottleneck events
- Invasive Species
- Habitat Fragmentation
What is Overexploitation?
Individuals are harvested at a faster rate than they can be replaced by reproduction, so recovery can’t occur
What happens if Overexploitation continues?
Continued Overexploitation can lead to extinction as the species will be unable to adapt to changing environmental conditions, due to a significant loss of Genetic Diversity
What are Bottleneck events?
Sudden events which cause a dramatic reduction in population size e.g. a disease outbreak, deforestation, natural disasters
What is a Bottleneck Effect?
When small populations lose the genetic diversity necessary to enable evolutionary responses to environmental change
What happens in small populations if a bottleneck event has occured?
Inbreeding will occur
What will happen if a population starts to inbreed after a bottleneck event?
Inbreeding depression and poor productive rates will occur and so the population may become extinct
What is a viable species?
A species able to self-sustain their popuation e.g. cheetahs due to naturally low genetic diversity despite bottleneck events
What is an Introduced Species?
Species that humans have moved either intentionally or accidentally to new geographic loctions
What is Naturalised Species?
Introduced Species that become established within wild communities
What are Invasive Species?
Invasive Species are Naturalised Species that spread rapidly in their new environment and eliminate native species
What do Invasive Species do?
Reduce Species Diversity
What is Habitat Fragmentation?
The process during which a large habitat is split into a number of smaller patches called fragents
What has Habitat Fragmentation led to?
The clearing of habitats (e.g. due to road building, deforestation)
What happens over time after Habitat Fragmentation?
The edges are degraded. This causes fragments to further decrease in size.
What do smaller habitat fragments lead to?
Smaller habitat fragments lead to increased competition between remaining species for limited resources
What does a smaller and more isolated habitat lead to?
A lower species diversity due to a decrease in species richness
What is a Habitat Corridor?
An area of natural habitat linking fragments seperated by human activities or structures
What can Habitat Corridors do?
They can remedy the negative effects of widespread habitat fragmentation by allowing movement of animals between fragments, increasing access to food and choice of mate.
What can Habitat Corridors also allow?
Recolonisation of small fragments by a species after local extinction
