Extinction Flashcards
Define extinction
Then end of a species or group of taxa
what is the difference between background extinction and mass extinction
Background = a continual, natural process
Mass = an accelerated rate of extinction that sharply reduces the Earth’s biodiversity
Define extinct in the wild
When individuals of a species only exist in captivity
Define locally extinct
When a species/ taxon is no longer present in an area previously inhabited
Define ecologically extinct
Species found in low numbers in a community so that they now have little impact on the ecology of a habitat
Define extirpation
the disappearance of a particular population, but not the entire species globally
What is the average rate of background extinction
Between 2-10 million years (average = 4)
When is extinction classed as mass extinction
at times when the earth loses more than ¾ of its species in a geologically short interval
How many mass extinctions has there been?
5
Name the 5 mass extinctions
Ordovician Devonian Permian Triassic Cretaceous
Which was the most famous mass extinction and why
Cretaceous - the extinction of the dinosaurs
Which extinction was the biggest?
Permian - over 95% of marine and 50% of all families globally were extinct
What likely caused the Permian extinction?
A massive perturbation (disturbance)
Name 3 types of species more likely to go extinct
Any from: Higher tropic levels Endemic species Specialists Migratory species Poor dispersers Smaller populations Species with complex lifecycles
Why are endemic species more at risk of extinction
Because they have limited/ restrictive distributions and geographic ranges meaning they are vulnerable to disturbance of those areas
Why are smaller populations more vulnerable to extinction?
Because they have less genetic variation in gene pools Leads to inbreeding Extinction vortex (pop. gets smaller = less genetic variation = smaller population)
What is an extinction vortex
the forces affecting small populations that cause them to spiral into a vortex of increasingly smaller populations and endanger their long-term survival
Which particular type of species has the most damaging affect on an ecosystem if lost
Key stone species
Name 3 extinct species
Stellas sea cow (1768) Great Auk (1844) Tasmanian Tiger (1933) Baji river dolphin (2006) Moa (1642) Dodo (1681) Passenger pigeon (1914)
What happened to the passenger pigeon?
There was 3-5 billion in mid 1800s (abundant)
Hunted to extinction
Extinct by 1914
Why were the passenger pigeons vulnerable to extinction?
They had complex lifecycles - needed to rest and raise chicks around lots of other pigeons – when numbers began to decline, they could no longer breed properly
What 2 main reasons cause species to go extinct
Disturbances
Small populations die out
Name 5 human causes of extinction
Habitat destruction and fragmentation Climate change Pollution Over exploitation Introduced/ alien species
Which anagram can help remember the human causes of extinction?
HIPPO
Habitat destruction Introduced species Pollution Population Overexploitation
What is the evil quartet?
Habitat destruction
Introduced species
Chains of extinction
Overkill
Define chains of extinction
When the extinction of one species caused by the extinction or decline of another species on which the first depends
Name 4 human causes of habitat destruction
Agriculture Urban development Deforestation Pollution Climate change
Which human factor do IUCN is the biggest threat to species?
Habitat destruction
Define relaxation
The loss of species from isolated habitats over time
Give 4 examples of endangered species on the IUCN list
Any from: Hawksbill turtles Golden Lion Tamarins Black Rhino (is increasing) Asian Elephant Rusty Patched Bumble Bee Malayan Tiger Pygmy three-toed sloth Mongoose Lemur Sunflower Seastar
What causes relaxation?
Fragmentation
Isolation
The separation of islands from mainland
What are edge effects
negative impacts adjacent to habitat boundaries
Which effect is caused by fragmentation
Edge effects
What is one human cause of invasive species?
Ship ballast water
Give 3 reasons forest edges make species more vulnerable
More sunlight Dryer Higher winds Less protection More predation Invasive species from outside the habitat
Which type of habitat will invasive species affect most negatively?
Isolated islands
Which case study if invasive species is known as Darwin’s Nightmare
Nile Perch, 1954
What happened in Lake Victoria in 1954 with Nile perch
Nile perch fish were introduced into lake victoria for human food
Perch annihilated the cichlid population
cichlids lacked defensive adaptations
Perch then had nothing to feed on and declined so couldn’t be used as a human food source
Which is a case study for invasive species through ship ballast water
Chinese Mitten crab
why are invasive species so successful?
Have no diseases, parasites or predators in the new area
They are usually better competitors than native species
They prey on vulnerable native species that lack defensive adaptions
Which 2 features of species make them the most vulnerable to exploitation?
K selected species
Species with restricted habitats (i.e: islands)
What are k selected species
those that possess relatively stable populations that fluctuate near the carrying capacity - they usually only have a few offspring and invest high amounts of parental care
Name 3 K selected species
Sharks
Elephants
Humans
bison
What is bycatch
The non-targeted species killed in fisheries
What is bush meat
harvest of wild animals for food
Which industry is worst for overexploitation?
Fisheries
What is another industry of overexploitation besides fisheries
Global trade - i.e: pets, plants, bekko, ivory, fashion
Which type of environment does pollution most effect?
Aquatic
What is bioaccumulation
process by which toxins concentrations increase in living tissues
Why is bioaccumulation so damaging to food chains?
concentrations increase through the food chain
Give 2 examples of bioaccumulation
Methylmercury
DDT (an insecticide)
What are endocrine disruptors?
chemicals/ compounds that interfere with the hormonal systems
Which threat causes endocrine disruptors?
Pollution - particularly chemical pollutants in aquatic systems
Name 2 examples of endocrine disruptors
TBT (Tributyltin) - anti-fouling paint on boats
Xenoestrogens - birth control
How do xenoestrogens affect marine species?
Causes freshwater fish to become intersex - effects reproductive rates
How does TBT (tributyltin) affect marine invertebrates?
Causes marine invertebrates to become imposex (i.e: dogwhelk females develop male genetalia)
What are the 4 types of genetic effects that can cause vulnerability in a species?
Bottlenecking
Inbreeding
Genetic Drift
Random Mutation
Why does a lack of genetic variation cause vulnerability?
Less genetic variation means less ability to adapt to environmental changes - so when a disturbance event occurs, a species cannot adapt (well) to survive it
