Threats to biodiversity Flashcards
What are the threats to biodiversity?
- direct exploitation
- changes to biotic facors
- changes to abiotic factors
- habitat destruction
- eradication of species
- introduced species
How is direct exploitation a threat to biodiversity?
- animals are exploited for a wide range of products
- or they are deemed dangerous or harmful
- illegal trade continues despite protections
What resources are animals exploited for?
- food
- fashion
- pets and entertainment
- furniture and ornaments
- traditional medicines
- other
Why is exploiting nature for food a threat to biodiversity?
- animals provide sustenance for humans , though sometimes illegal and unsustainable and can lead to a dramatic decrease in wild populations. Monocultures decrease biodiversity and the land can be overused. Fishing quotas and net sizes are introduced.
e.g. swordfish, shark, many species of fish
- this has led to some extinctions e.g. dodo, great auk, passenger pigeon
Why is exploiting nature for fashion a threat to biodiversity?
- animal skins have been used as clothing throughout history, but some animals are over exploited
e.g. snake/crocodile skins for shoes and bags, fur from snow leopards and fur seals for fur coats and accessories, feathers from birds such as kingfishers and ostriches
- fur seals were nearly hunted to extinction for their skins in 1900s
Why is exploiting nature for pets and entertainment a threat to biodiversity?
pets:
animals are taken from the wild usually in the illegal pet trade to be pets. This is
- cruel
- dangerous
- reduces wild population
e.g. snakes, parrots
house plants:
species of wild tropical plant are often taken from the wild to be sold or kept in houses
- not the right conditions
- impacts food chain
zoos:
used to be more common to take wild animals but due to animal rights laws now most zoos are part of breeding programmes and conservation efforts such as increasing the gene pool
aquaria:
marine fish do not breed well in aquariums because conditions for breeding are not fully understood. Most taken from wild and decimates wild populations e.g. Banggai Cardinalfish is endangered
marine life centres:
dolphins and orcas caught in the wild then kept in enclosures that are far too small
Why is exploiting nature for furniture and ornaments a threat to biodiversity?
- many species selectively kept/bred for attractive characteristics that can be sold when the animal is killed. Often in an illegal trade
e.g. The Great Elephant Census
- 352,271 African Savannah Elephants in 18 countries
- down 30% between 2007-14
- pop decreasing 8% per year due to poaching
- 84% sightings in protected areas
- high number of elephant carcasses are spotted both inside and outside protected areas
- elephants ivory is highly coveted for ornaments, jewellery, piano keys
e.g. shark teeth, coral and shells are sold as souvenirs and jewellery
e.g. illegal exports of wood such as mahogany and teak from the tropical rainforest
Why is exploiting nature for traditional medicine a threat to biodiversity?
- trad medicines are in high demand e.g. Asia has led to a large number of select species being collected despite lack of evidence that they work. As populations decline, they become unavailable, and it turns to the illegal trade
e.g. tigers - claws as sedative, tail for skin diseases
rhinos - horn for nosebleed and smallpox
seahorses - treat infertility and arthritis
Why is exploiting nature for other products a threat to biodiversity?
whale blubber used to make oil
- used until 1970s to make lamp oil, candles, soap etc.
- now been replaced with oil from jojoba plant
- extremely cruel and unsustainable
How is eradication of species a threat to biodiversity?
species are killed because they interfere with human activities or threaten humans
e.g.
- FEAR and DANGER: poisonous snakes and crocs
- DISEASE: pathogen vectors (mosquitos)
- FARMING: livestock predators (wolves), crop pests (insects)
What changes in abiotic factors are a threat to biodiversity?
- water availability
- temperature
- water turbidity
- dissolved oxygen
- pH
- physical damage
What are the biotic factors that are a threat to biodiversity?
- pollinators
- seed dispersal species
- food chain impacts
How do introduced species threaten biodiversity?
- original species already adapted
- introduced may have adaptations to outcompete
- indigenous die out
ESPECIALLY ISLANDS = small number of colonising species with little outside world contact
What kinds of introduced species threaten biodiversity?
INTRODUCED:
- competitors
- predators
- pathogens
- species that hybridise
LOSS:
- species that control abiotic factors (due to introduced species)
Give an example of an introduced competitor species
grey squirrel - from N. America
It can digest oak acorns that reds cannot - better adapted to exploit available British food
It is bigger and more aggressive- out compete reds for nesting sites
Pop dropped from 3.5m to 120,000 since 1870
Give an example of an introduced predator species
Cats introduced to Stephens Island 1890s
Hunted the Stephens Island wren - is now extinct
Give an example of introduced species carrying pathogens
Grey Squirrel from N. America- carries squirrel pox virus that does not affect the greys but kills indigenous reds
Give an example of introduced species that hybridise and explain why hybridisation occurs
If an introduced species is closely related to an indigenous one, then cross breeding may produce fertile hybrids, changing the natural gene-pool.
Scottish Wildcat population is threatened with hybridisation from domestic cats
Explain why loss of species that control abiotic factors is detrimental, and give an example
Interdependence between species means that some species change habitats/produce abiotic factors that other species need for survival
African Forest Elephants create clearing and water holes that other species rely on for water, such as baboons
What human activities threaten biodiversity through habitat destruction?
Land use change:
- deforestation
- ploughing of grassland
- reservoir creation
- draining of wetlands
- mineral extraction
- urban expansion
What are the 5 IUCN criteria to categorise threatened species?
- Population decline over previous 10 years/3 generations
- Geographic range
- Small pop size/number of areas where found
- Number of mature adults (population size)
- Probability of extinction
Which species were categorised in:
2013
2014
2015
2016
2013 - Okapi, from Near Threatened to Endangered. Only found in DRC - forest habitat destruction, hunting, conservation difficulties in military conflict
2014 - 22/100 Lemur Crit. Endan. Only found Madagascar - habitat loss and bushmeat
2015 - White-headed vulture, from Vulnerable to Crit. Endan.
Poisoning and persecution e.g. Zambia, Malawi
2016 - Plains Zebra, from Least Conc. to Near Threatened due to mainly habitat loss, Sub Saharan Africa
Is there one good method to conserve endangered species?
No - the most successful conservation programmes involve a combination of methods
What percentage of species have been documented:
plants on land
animals on land
fungi on land
plants on land = 72%
animals on land = 12%
fungi on land =7%
What percentage of species are undiscovered:
land species
marine species
land species = 86%
marine species= 91%
What is ‘background extinction rate’?
How does it relate to the current extinction rate?
extinctions naturally occurring all the time
current extinction rates are 100-1000x this rate
1000 species gone extinct in the past 500 years
What is a biodiversity hotspot?
regions containing high levels of biodiversity, several endemic species and a significant number of threatened/endangered species
What are the two criteria an area has to meet to be classed as a biodiversity hotspot?
How many biodiversity hotspots are there?
Give an example
- at least 1,500 endemic species
- over 70% original habitat already lost
34 BPH
e.g. Madagascar
95% plants (11,200), 85% animals are endemic e.g. Lemurs
What is an endemic species?
a species found in a single geographical location and do not occur naturally anywhere else e.g. islands
e.g. ring-tailed lemur is endemic to Madagascar
How do we know a species is being threatened?
data about species and populations and habitats is always being collected by many thousands of different groups of scientists, organisations and governments
What is a biome?
areas with similar climate and landscape containing communities of plants and animals that have adaptations to that particular environment
What is the importance of high species diversity?
- brings greater stability and enables the ecosystem to recover faster after disruption
- ecosystems with higher species diversity are more resilient because there is a greater range of niches and more species interactions
Give some seagrass ecosystem services
- carbon sequestration
- habitat: high biodiversity
- recreational and tourism
- genetic/medicinal resources
- erosion control
