Threats to biodiversity

Question 1

What is extinction?

Answer 1

When a species ceases to exist after the last individual in that species dies.

Question 2

What factors help to maintain biodiversity?

Answer 2

Complexity of the ecosystem
Stage of succession
Limiting factors
Inertia

Question 3

How does complexity of the ecosystem help maintain biodiversity?

Answer 3

If one prey or food source in a complex food web is lost, the others can fill the gaps.

Question 4

How does the stage of succession help to maintain biodiversity?

Answer 4

Species diversity increases as succession proceeds until a climax community is reached. Ecosystems in late stages of succession will therefore be more resilient than young ecosystems as they have more (genetic) diversity.

Question 5

How do limiting factors effect biodiversity?

Answer 5

If abiotic factors required for life are in abundance, the ecosystem is more likely to survive if one is then reduced.

Question 6

How does inertia effect biodiversity?

Answer 6

Inertia is the property of an ecosystem to resist change when subjected to a disruptive force.

Question 7

What are natural hazards?

Answer 7

Naturally occurring events that may have a negative impact on the environment.

Question 8

When is a natural hazard considered a natural disaster?

Answer 8

After it reaches a certain scale. Usually when it impacts humans badly.

Question 9

What are environmental disasters?

Answer 9

Usually thought of as caused by human acrivity, e.g. oil spills.

Question 10

What is the major cause of loss of biodiversity?

Answer 10

Loss of habitat

Question 11

What is fragmentation of habitat?

Answer 11

When a habitat is divided up unto a patchwork of fragments, separated by human infrastructure.

Question 12

What are the effects on fragmented habitats?

Answer 12

They are essentially islands as they become isolated from the rest of the habitat. There are edge effects to the islands with higher edge to area ratios as light, temperature and humidity fluctuates more around the edge than the middle.
Also invasion of species becomes easier
Wild species can come in contact with domesticated species and diseases could spread

Question 13

In what ways can pollution destroy habitats?

Answer 13

Local pollution, spraying pesticides or oil spills
Environmental pollution can lead to acid deposition or photochemical smog
Run off fertilisers can cause eutrophication or chemicals to accumulate in food chains
Climate change alters weather patterns and shifts biomes away from the equator.

Question 14

How do we know if the population is unsustainable?

Answer 14

If we exceed the maximum sustainable yield of any species. This is the maximum that can be harvested each year and replaced by natural population growth.

Question 15

How are tropical animals overexploited?

Answer 15

For the pet trade

Question 16

Is the introduction of non native species always unsuccessful?

Answer 16

No. Potatoes were introduced to Europe from the Americas

Question 17

Example of unsuccessful introduction of non native species?

Answer 17

Introduction of cane toads in Australia

Question 18

Example of extinction by disease?

Answer 18

Black footed ferrets wiped out by disease.

Question 19

What makes a species prone to extinction?

Answer 19

Narrow geographical range
Small population size or declining numbers - low genetic diversity
Low population densities and large territories
Few populations of the species
A large body
Low reproductive potential
Seasonal migrants
Poor dispersers
Specialised feeders or niche requirements
Edible to humans and herding together

Question 20

Why is a narrow geographical range bad?

Answer 20

If that small area gets destroyed, their entire habitat is gone.

Question 21

Why is small population size or declining numbers bad?

Answer 21

Less genetic diversity so less resilient to change. Leads to more inbreeding.

Question 22

Why is low population densities and large territories bad?

Answer 22

Habitat fragmentation can stop species meeting each other if they don’t don’t have high population numbers (hang out alone).

Question 23

Why are few populations of the species bad?

Answer 23

They are their only chance of survival. Hard to recover.

Question 24

Why is a large body bad?

Answer 24

Top predators suffer most from biomagnification, they need more food and compete with humans. They also have large ranges. Some are hunted for sport or value.

Question 25

Why is low reproductive potential bad?

Answer 25

The population takes a long time to recover. They only have one child per pair per year.

Question 26

Why are seasonal migrants bad?

Answer 26

Hazardous journey, long travels, they need habitats at both ends of the migration route. If one is destroyed they may starve. There may also be barriers on the journey.

Question 27

Why are poor dispersers bad?

Answer 27

If biome shift happens, they’re fucked. Plants can hardly migrate easily with seed dispersal. Also flightless birds can’t travel far.

Question 28

Why are specialised feeders bad?

Answer 28

Golden bamboo lemur depends on bamboo and if it doesn’t grow due to climate change then they can’t adapt.

Question 29

Why are animals that are edible to humans bad?

Answer 29

Overhunting or overharvesting can eradicate a species quickly.

Question 30

Why are island organisms particularly vulnerable?

Answer 30

Populations tend to be small
Islands have a high degree of endemic species
Genetic diversity tends to be low
Islands tend to be vulnerable to the introduction of non native species

Question 31

What is the IUCN red list?

Answer 31

determines the conservation status of a species based on several criteria.

Question 32

What ar the IUCN Red list criteria?

Answer 32

• Extinct
• Extinct in the wild
• Critically endangered
• Endangered
• Vulnerable
• Near threatened
• Least concern
• Data deficient
• Non evaluated

Question 33

What factors effect the red list?

Answer 33

Population size
Degree of specialisation
Distribution
Reproductive potential and behaviour
Geographic range
Degree of fragmentation
Quality of habitat
Trophic level
Probability of extinction