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Biodiversity and Conversation > L7: Extinction > Flashcards

L7: Extinction Flashcards

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Conversation Starters flashcards
1
Q

What types of extinction are there?

A

-Local extinction
-Extinct in the wild
-Ecological / Functional extinction
-Extinction debt
-Numerical extinction

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2
Q

What is local extinction?

A

-When an organism is no longer found in a specific area it once inhabited, but found in the rest of the world
eg. grey wolf in Ireland

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3
Q

What does extinct in the wild mean?

A

-Only exists in ex-situ institutes
eg. Spix’s Macaw Cyanopistta spixii

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4
Q

What is ecological extinction?

A

-When very small numbers remain
-Effects on other species in community are negligible
-Probability of survival of species is low

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5
Q

What is an example of species being ecologically extinct?

A

-Hawksbill turtle
-Prey for sharks, crocodiles, octopuses and human
-Shells are hunting trophies
-Entanglement in fishing gear occurs
-Specialise in eating sponge species on reefs which allows for other species to grow
-Sponges are now overtaking coral reefs, decrease in reef biodiversity, can suffocate corals

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6
Q

Describe extinct debt.

A

-Time lag between environmental disturbance affecting a species and its final disappearance
-Reflects future ecological cost
-The living dead / zombie species
-Small remnant populations
-Species with long generation times, near extinction threshold
-Can cause underestimation of currently endangered species.

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7
Q

What is numerical extinction?

A

-When the last existing member of a species dies / there are no individuals left to reproduce

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8
Q

What is an example of a numerically extinct species?

A

-Western Black Rhinoceros
-Extinct in 2011
-Increased demand for illegal rhino horn decimated the species

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9
Q

Describe the extinction vortex.

A

Small fragmented isolated populations ->
Inbreeding, loss of genetic diversity ->
Reduced adaptability survival and reproduction ->
Reduced population size ->

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10
Q

What is one biggest drivers of extinction?

A

-Habitat degradation

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11
Q

What are the main drivers of extinction?

A

-Habitat degradation
-Predation / invasive species
-Overexploitation
-Pollution
-Climate change

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12
Q

What are examples of species affected by habitat loss?

A

Javan / Silvery Gibbon (Hylobates moloch)
98% of original habitat has been destroyed
Less than 5000 individuals remain
Freshwater pearl mussel (margaritifera margaritifera) susceptible to sedimentation of river channels

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13
Q

Describe habitat degradation.

A

-Both natural and anthropogenic origins
-Eg. Amazon rainforest fires 2019 >9000 km 2
Can cause direct mortality
Can lead to increased competition for limited resources

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14
Q

Describe predation and invasive species impacts.

A

-Contributing factor to 33% of known animal extinctions
-Cats, rats and snakes
-Direct mortality
-Competition for resources
-Introduce diseases
-Habitat modification

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15
Q

How does invasive species affect New Zealand?

A

-Kill around 25 million native birds per year, including Kiwis
-Natives did not evolve with predators, very vulnerable to invasive species
-Plan to eradicate rats, stoats and possums by 2050 with trapping programme.

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16
Q

What is an example of an invasive species going out of control?

A

70% of Polynesian Tree snail driven to brink of extinction.
-Cause due to invasive carnivorous snail Euglandina rosea which was introduced to control another invasive species, African land snail
-Native snail was smaller and slower and easy prey

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17
Q

Describe an example of overexploitation.

A

-Passenger pigeon
-3-5 billion in North America before Europeans
-1850s large scale commercials hunting of pigeons
-1900s extinct in wild, last known individual Martha died in captivity 1914

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18
Q

Describe an example of pollution.

A

Yangtze river dolphin, used to be 5000 - 6000 dolphins in 1950s
-1998 only 13 left
-Driven to extinction by pollution, electrofishing, engineering explosions, inbreeding, fishing gear
-Last individual in captivity dead in 2002
Declared functionally extinct in December 2006

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19
Q

Describe a case of extinction due to climate change.

A

-Bramble cay melomys
-First mammal driven to extinction by climate change in 2015
-Habitat destroyed by rising sea levels
-Found on Bramble Cay island in Great Barrier Reef

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20
Q

Why is it important to identify vulnerable species?

A

-Some species are more at risk than others
-Population viability analyses an option
-Conservation biology often requires rapid assessment and decision making
-Reliable and easily measured indicators of extinction risk is important

21
Q

What does intrinsic mean?

A

Inherent factors directly relating to the species, biological and ecological

22
Q

What does extrinsic mean?

A

Environmental factors, usually human activities

23
Q

What intrinsic traits drive species extinction?

A

-Population size / number of populations
-Narrow geographical ranges
-Habitat specialists
-Rare species
-Body size

24
Q

What extrinsic factors are correlated with extinction?

A

-Commercial value of species
-Commercial value of habitat
-Whether population or habitat is protected
-Whether there is laws protecting the species

25
Q

How does population size affect a species?

A

-Some species have naturally small populations like large populations with large territories
-Greater vulnerability to stochastic factors
-Best predictor of extinction rate of isolated populations
-Species with several populations less vulnerable

26
Q

How does a narrow geographical range affect a species?

A

-Linked to population size
-May be endemic
-Many rare species occupy islands or isolated habitats, eg. snow leopard

27
Q

How many snow leopards are left in the wild?

A

2000 -3000 left

28
Q

What is the home ranges of snow leopards?

A

30 - 62 km2 where prey is abundant
>1,000 km2 where prey is rare

29
Q

How does being a habitat specialist affect a species?

A

-May need specialist habit
-Alternation of ecosystem can result in an unsuitable habitat
-Parasites (co-extinction)

30
Q

What is some examples of habitat specialists?

A

-Wetland plants require very specific and regular changes in water levels
-These may be rapidly changed by human activity changing the hydrology of the system
-Salt marsh cord grass Spartina patens, is only found in salt marshes and no where else

31
Q

What is the name of the tongue eating parasite?

A

Cymothoa exigua
-Parasitizes eight species of fish

32
Q

What makes a species rare?

A

1- Only found in small populations
2- Lives in a narrow geographical range
3- Occupies only one or a few specialised habitats

33
Q

What is specialisation?

A

“Use of a relatively restricted subset of resources or habitats compared with other species”
-Koalas- limited diet of eucalyptus leaves
-Palm-nut vulture- eats fruit from the oil palm
-Life-history specialization, like migration

34
Q

How does body size affect a species?

A

Large animals have
-Large ranges
-Low reproductive rates
-Require more food
-Are hunted by humans

-Most extinctions were of the largest animals such as woolly mammoths and the Tasmanian tiger

35
Q

What intrinsic factors affect orangutans?

A

-Long lived species
-Late reproduction (10-15 years)
-Long interbirth periods
-Low birth rate (1 or 2 offspring)

36
Q

What are the two species of orangutans?

A

-Pongo abelii (Sumatra)
-Pongo pygmaeus (Borneo)

37
Q

How long do orangutans live for?

A

Up to 50 years

38
Q

How long is the interbirth period for orangutans?

A

Once every 5 years

39
Q

What species are most at risk of extinction?

A

-Large specialised species that live in narrow geographic ranges most at risk of extinction

40
Q

How does commercial value of species affect them?

A

-They be overexploited
-Elephants value of ivory tusks

41
Q

How does commercial value of habitats affect species?

A

-Large scale of forest turned into oil palm plantations
-Industry worth US$67 bn
-Estimated 25million hectares destroyed in Borneo and Sumatra
-Orangutan is flagship species

42
Q

How does the existence of protective legislation affect species?

A

Endangered species act played a role in return of grey wolves to Yellowstone, rollback of this law is now a new threat for this species

43
Q

How many marine mammals are threatened with extinction?

A

25%

44
Q

What are drivers of threats against marine mammals?

A

-Fishing
-Invasive species
-Development
-Hunting
-Climate change
Almost half are threatened by 2 or more human impacts

45
Q

What marine mammal species are at high risk?

A

-Species with low reproductive rates
-Slow life histories
-River dolphins with narrow ranges
-Family Phocidae (seals) and famliy diphiidae (beaked whales)

46
Q

What marine mammals are at lower risk?

A

-Toothed whales- low reproduction but large range and social groups
-Baleen whales, like Humpbacks and Greys
-Fast life histories, strong recoveries after bans on whaling

47
Q

What are the conclusions of this lecture?

A

-Most important predictor- speed of life history as potential to rebound from human impacts
-Intrinsic traits are more important predictors of risk
-Measure the inherent susceptibility to human impacts and ability to recover from them
-Emphasizes the importance of understanding the basic biology and ecology of marine mammals

48
Q

What is the summary of this lecture?

A

-Rare and specialised species are more prone to extinction
-Species with slow life histories are more prone to extinction

Biodiversity and Conversation (12 decks)

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