Threats to biodiversity Flashcards
What is extinction?
When a species ceases to exist after the last individual in that species dies.
What factors help to maintain biodiversity?
Complexity of the ecosystem
Stage of succession
Limiting factors
Inertia
How does complexity of the ecosystem help maintain biodiversity?
If one prey or food source in a complex food web is lost, the others can fill the gaps.
How does the stage of succession help to maintain biodiversity?
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.
How do limiting factors effect biodiversity?
If abiotic factors required for life are in abundance, the ecosystem is more likely to survive if one is then reduced.
How does inertia effect biodiversity?
Inertia is the property of an ecosystem to resist change when subjected to a disruptive force.
What are natural hazards?
Naturally occurring events that may have a negative impact on the environment.
When is a natural hazard considered a natural disaster?
After it reaches a certain scale. Usually when it impacts humans badly.
What are environmental disasters?
Usually thought of as caused by human acrivity, e.g. oil spills.
What is the major cause of loss of biodiversity?
Loss of habitat
What is fragmentation of habitat?
When a habitat is divided up unto a patchwork of fragments, separated by human infrastructure.
What are the effects on fragmented habitats?
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
In what ways can pollution destroy habitats?
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.
How do we know if the population is unsustainable?
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.
How are tropical animals overexploited?
For the pet trade
Is the introduction of non native species always unsuccessful?
No. Potatoes were introduced to Europe from the Americas
Example of unsuccessful introduction of non native species?
Introduction of cane toads in Australia
Example of extinction by disease?
Black footed ferrets wiped out by disease.
What makes a species prone to extinction?
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
Why is a narrow geographical range bad?
If that small area gets destroyed, their entire habitat is gone.
Why is small population size or declining numbers bad?
Less genetic diversity so less resilient to change. Leads to more inbreeding.
Why is low population densities and large territories bad?
Habitat fragmentation can stop species meeting each other if they don’t don’t have high population numbers (hang out alone).
Why are few populations of the species bad?
They are their only chance of survival. Hard to recover.
Why is a large body bad?
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.
Why is low reproductive potential bad?
The population takes a long time to recover. They only have one child per pair per year.
Why are seasonal migrants bad?
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.
Why are poor dispersers bad?
If biome shift happens, they’re fucked. Plants can hardly migrate easily with seed dispersal. Also flightless birds can’t travel far.
Why are specialised feeders bad?
Golden bamboo lemur depends on bamboo and if it doesn’t grow due to climate change then they can’t adapt.
Why are animals that are edible to humans bad?
Overhunting or overharvesting can eradicate a species quickly.
Why are island organisms particularly vulnerable?
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
What is the IUCN red list?
determines the conservation status of a species based on several criteria.
What ar the IUCN Red list criteria?
- Extinct
- Extinct in the wild
- Critically endangered
- Endangered
- Vulnerable
- Near threatened
- Least concern
- Data deficient
- Non evaluated
What factors effect the red list?
Population size Degree of specialisation Distribution Reproductive potential and behaviour Geographic range Degree of fragmentation Quality of habitat Trophic level Probability of extinction