Key Area 7 & 8: Components & Threats to Biodiversity

Question 1

What is Biodiversity?

Answer 1

A measurement of the total variety of life in a particular area

Question 2

The overall biodiversity of Earth can be estimated into what 3 components?

Answer 2

1. Genetic Diversity
2. Ecosystem Diversity
3. Species Diversity

Question 3

What is Genetic Diversity?

Answer 3

The number and frequency of all the alleles within a species

Question 4

If one population of species dies out (local extinction) what happens?

Answer 4

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

Question 5

What is Ecosystem Diversity?

Answer 5

The number of distinct ecosystems within a defined area

Question 6

What is Species Diversity?

Answer 6

Species diversity is detemined by the species richness and relative abundance of species in an ecosystem.

Question 7

What is Species Richness?

Answer 7

The number of different species in an ecosystem

Question 8

What is Relative Abundance?

Answer 8

The proportion of each species in the ecosystem

Question 9

What is a Dominant Species?

Answer 9

A species that has a high relative abundance in a community

Question 10

What happens if a community does/doesn’t have a Dominant Species?

Answer 10

A community with a dominant species has a lower Species Diversity than one with the same Species Richness but no particularly Dominant Species

Question 11

What are the 4 Threats to Biodiversity?

Answer 11

1. Overexploitation
2. Bottleneck events
3. Invasive Species
4. Habitat Fragmentation

Question 12

What is Overexploitation?

Answer 12

Individuals are harvested at a faster rate than they can be replaced by reproduction, so recovery can’t occur

Question 13

What happens if Overexploitation continues?

Answer 13

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

Question 14

What are Bottleneck events?

Answer 14

Sudden events which cause a dramatic reduction in population size e.g. a disease outbreak, deforestation, natural disasters

Question 15

What is a Bottleneck Effect?

Answer 15

When small populations lose the genetic diversity necessary to enable evolutionary responses to environmental change

Question 16

What happens in small populations if a bottleneck event has occured?

Answer 16

Inbreeding will occur

Question 17

What will happen if a population starts to inbreed after a bottleneck event?

Answer 17

Inbreeding depression and poor productive rates will occur and so the population may become extinct

Question 18

What is a viable species?

Answer 18

A species able to self-sustain their popuation e.g. cheetahs due to naturally low genetic diversity despite bottleneck events

Question 19

What is an Introduced Species?

Answer 19

Species that humans have moved either intentionally or accidentally to new geographic loctions

Question 20

What is Naturalised Species?

Answer 20

Introduced Species that become established within wild communities

Question 21

What are Invasive Species?

Answer 21

Invasive Species are Naturalised Species that spread rapidly in their new environment and eliminate native species

Question 22

What do Invasive Species do?

Answer 22

Reduce Species Diversity

Question 23

What is Habitat Fragmentation?

Answer 23

The process during which a large habitat is split into a number of smaller patches called fragents

Question 24

What has Habitat Fragmentation led to?

Answer 24

The clearing of habitats (e.g. due to road building, deforestation)

Question 25

What happens over time after Habitat Fragmentation?

Answer 25

The edges are degraded. This causes fragments to further decrease in size.

Question 26

What do smaller habitat fragments lead to?

Answer 26

Smaller habitat fragments lead to increased competition between remaining species for limited resources

Question 27

What does a smaller and more isolated habitat lead to?

Answer 27

A lower species diversity due to a decrease in species richness

Question 28

What is a Habitat Corridor?

Answer 28

An area of natural habitat linking fragments seperated by human activities or structures

Question 29

What can Habitat Corridors do?

Answer 29

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.

Question 30

What can Habitat Corridors also allow?

Answer 30

Recolonisation of small fragments by a species after local extinction