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Biodiversity And Conservation > Extinction > Flashcards

Extinction Flashcards

1
Q

Extinction in the Holocene era (10,000 years ago)

A

Largest ground sloth was the size of an elephant.
Claws could reach 50cm in length.
Ground sloth was nothing like other animals, tiny head, slim shoulders and massive hind quarters.
Herbivores like their modern day tree sloth predecessors.

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2
Q

What is there a long term balance between

A

Rates of speciation and extinction

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3
Q

How can an equilibrium species richness be predicted

A

Based on rates of extinction and speciation among existing species

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4
Q

How many species have evolved on earth over the last 3.5 billion years

A

4 billion

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5
Q

What percentage of the 4 billion species have gone

A

99%

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6
Q

What does the species we have today represent

A

A very small proportion of what has been living in the planet

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7
Q

How many mass extinctions has there been

A

5 so far

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8
Q

What are mass extinctions

A

Times when the earth loses more than three quarters of its species in a geologically short interval

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9
Q

What are the names of the extinction events

A 
Ordovician 
Devonian 
Permian
Triassic
Cretaceous
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10
Q

How much did the Ordovician event lose

A

86%

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11
Q

How much did the Devonian event lose

A

75%

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12
Q

How much did the Permian event lose

A

96%

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13
Q

How much did the Triassic event lose

A

80%

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14
Q

How much did the Cretaceous event lose

A

76%

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15
Q

The main causes of the Ordovician event

A

Onset of alternating glacial and interglacial episodes

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16
Q

The main causes of the Devonian event

A

Global cooling followed by warming, tied to diversification of plants

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17
Q

The main causes of the Permian event

A

Siberian volcanism and global warming

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18
Q

The main causes of the Triassic event

A

Elevated co2 levels increasing temperature and ocean acidification

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19
Q

The main causes of the Cretaceous event

A

A meteor causing a global cataclysm and caused cooling . May have also been climate change before

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20
Q

What do mass extinctions account for

A

4% of total extinctions (background rate is high)

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21
Q

What do mass extinctions do

A

Disrupt overall development of diversity

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22
Q

What do survivors of mass extinctions tend to be

A

Generalists and opportunists

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23
Q

How long does it take after a mass extinction to recover biodiversity

A

10 million years

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24
Q

What is the lifespan of all species

A

1 million

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25
Q

What does the IUCN red list data say about extinction

A

27,000 species are threatened.
14% birds
25% mammals
40% amphibians

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26
Q

Why is speciation not a relevant time frame to ya

A

Because time frame for speciation isolation is longer than extinction

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27
Q

What are traits promoting survival

A 
R-selected traits
Large populations.
Widespread.
High genetic variability.
Rapid dispersal.
Human commensalism.
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28
Q

Traits promoting extinction

A 
K-selected traits.
Small populations.
Rare. 
Low genetic variability.
Slow dispersal.
Exploited by humans.
29
Q

What are r species

A

Opportunistic pioneers. They have been selected for their ability to reproduce rapidly

30
Q

What are k species

A

Specialists. Have features that favour populations remaining close to the habitats carrying capacity

31
Q

Example of an r selected species

A

Brown rat

6 rats per pregnancy and 6 generations a year

32
Q

Example of a k selected species

A

African elephant

1 calf per female every 5 years

33
Q

What is the potential growth of the female population of rats vs elephants

A

Over 2 trillion female rats but only 2.4 female elephants

34
Q

What are the features to look at for r and k species

A 
Habitat
Populations 
Body size
Growth 
Time to mature 
Reproductive period
Offspring
Parental care 
Adult mortality
Dispersal ability
35
Q

What is the habitat like for r species

A

Unstable, unpredictable

36
Q

What is the population like for r species

A

Fluctuate widely

37
Q

What is the body size like for r species

A

Small

38
Q

What is the growth like for r species

A

Rapid

39
Q

What is the time to mature like for r species

A

Short

40
Q

What is the habitat like for k species

A

Stable and predictable

41
Q

What is the populations like for k species

A

Close to carrying capacity

42
Q

What is the body size like for k species

A

Large

43
Q

What is the growth like for k species

A

Slow

44
Q

What is the time to mature like for k species

A

Long

45
Q

What is the offspring like for k species

A

Many, small

46
Q

What is the parental care like for k species

A

Little or none

47
Q

What is the adult mortality like for k species

A

High

48
Q

What is the dispersal ability like for k species

A

High

49
Q

What is the offspring like for r species

A

Few, large

50
Q

What is the reproductive period like for k species

A

Longer

51
Q

What is the parental care like for k species

A

High

52
Q

What is the adult mortality like for k species

A

Low

53
Q

What is the dispersal ability like for k species

A

Low

54
Q

How does population size affect extinction

A

Initial population size defines likelihood of extinction for both animals and birds e.f small is more likely

55
Q

How does range size affect extinction

A

Small geographic ranges (species endemic to islands) means more extinction

56
Q

What are the demographic reasons about why small and isolated population so vulnerable

A

Unequal sex ratio.
Low change of locating a reproductive partner.
Low fecundity due to age, illness.
Low cooperative interaction in food acquisition, predator detection.

57
Q

Example of a skewed sex ratio

A

Selecting hunting of males in elephants seals leads to skewed sex ratio.
Males:females.
10:90 means only 36 are the effective population

58
Q

How does genetic variation affect extinction

A

Small populations means low genetic diversity and low genetic diversity limits the ability to respond to new conditions and causes inbreeding depression - leads to higher offspring mortality.

59
Q

How does dispersal ability affect extinction

A

High dispersal ability you have lowest rate of extinction to proportion going extinct. Being able to disperse reduces vulnerability to extinction.

60
Q

How does relationship with humans affect extinction

A

Some species benefit from humans (commensal species derive food or other benefits from another organism without hurting or helping it) but others have antagonistic relationships with humans.

61
Q

What is the most likely explanation for global extinction of megafauna in pleistocene

A

Humans or maybe climate change - depends where and and the species. Synergetic effect. In Africa it’s mainly climate change but in the America it’s mainly humans

62
Q

What are the parts of the extinction vortex

A

A mix of directional factors, genetic problems and stochastic factors all affecting each other.

63
Q

What are directional factors

A

Habitat loss
Pollution
Over exploitation
Exotic species

64
Q

What are the stochastic factors

A

Demographic stochasticity
Environmental variations.
Catastrophes.

65
Q

What is the extinction vortex

A

Small fragmented isolated populations -> inbreeding loss of genetic diversity -> reduces adaptability, survival and reproduction -> reduced N -> back to the beginning

66
Q

What are the predispositions to extinction

A 
Rarity (small range, small populations)
Large, slow growing and long lived.
Large area requirements.
Top of food web/conflict with humans.
Specialised needs.
Adapted to core habitats.
Poor dispersal/insular.
67
Q

How do forest edge effects on populations

A

Some species use corridors between rainforest patches e.g generalist ants but others can’t live in the disturbed environment e.g forest specialised ants.

68
Q

What animals has a large area requirements and conflict with humans

A

Eurasian wolf

Biodiversity And Conservation (10 decks)

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