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IB Environmental Systems and Societies > Chapter 3 > Flashcards

Chapter 3 Flashcards

1
Q

Species diversity

A

A type of biodiversity which is a product of two variables, the number of species (richness) and their relative proportions (evenness)

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2
Q

Species diversity key points

A

Both the range (variety) and number of organisms (abundance) not just the total number of organisms, but the number of organisms WITHIN each of the different species

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3
Q

Genetic diversity

A

The range of genetic material present in a gene pool or population of a species

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4
Q

Habitat diversity

A

The range of different habitats per unit area in a particular ecosystem

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5
Q

High biodiversity advantages

A

Resilience and stability due to range of plants present of which some will survive droughts, floods, insect attack, disease

Genetic diversity - resistance to diseases

Plants will have deep roots - can cycle nutrients and bring them to the surface making them available for other plants

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6
Q

High biodiversity disadvantages

A

Diversity could be the result of fragmentation of a habitat or degradation - species richness is due to pioneer species invading bare areas quickly

Managing grazing can be difficult - plant species have different requirements and tolerance to grazing

Some stable/healthy communities have few plant species - an exception to the rule

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7
Q

Biodiversity hotspot

A

A region with a high level of biodiversity that is under threat from human activities

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8
Q

Diversity indices

A

Accurately compare two similar ecosystems/communities

Low diversity - pollution, eutrophication, recent colonization of a site, number of species present

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9
Q

Hotspot key points

A

Mostly in tropical rainforests, nearer the tropics (fewer limiting factors there)

ALL threatened areas, 70% of habitat has already been lost

Habitat contains more than 1,5000 plant species, cover only 2.3% of the land species

Large densities of human habituations nearby

Useful models to focus our attention on habitat destruction and threats to unique ecosystems/species

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10
Q

How hotspots can be ‘misleading’

A

Focus on vascular plants, ignore animals

Do not represent total species diversity or richness

Focus on regions where habitats have been lost (or still are)

Do not consider genetic diversity

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11
Q

Speciation

A

The formation of new species when populations of a species become isolated and evolve differently

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12
Q

Speciation (long definition)

A

The gradual change of a species over a long time. When populations of the same species become separated, they cannot interbreed and if the environments they inhabit change they may start to diverge and a new species forms. Humans can speed up speciation by artificial selection of animals and plants and by genetic engineering but the natural process of speciation is a slow one. Separation may have geographical or reproductive causes

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13
Q

The theory of evolution

A

Proposed by Charles Darwin in The Origin of Species - 1859

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14
Q

The theory of evolution key points

A

Each individual is different (except identical twins) due to their particular set of inherited genes and mutations

Each will be differently adapted to the environment

Resources are limited - there will be competition

Over time these changes show and the whole population changes

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15
Q

Natural selection

A

The idea where those more adapted to their environment will have an advantage and flourish and reproduce

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16
Q

Survival of the fittest

A

The fittest survive

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17
Q

Physical barriers

A

Species can develop into two or more new species if their population is split by some kind of physical barrier, like a mountain rang or ocean

Splits the gene pool

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18
Q

Land bridges

A

Allow species to invade new areas (eg North and South America were separated for a long time, but now there is a land bridge of Central America)

Species begin to mix

Caused by lowering of seawater levels

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19
Q

Continental drift

A

Definition: when seven large tectonic plates and many smaller ones drift around, moving at about 50 to 100 mm per year

Continents move to different climate zones - species have to adapt, higher biodiversity

E.g. Antarctica used to have a tropical climate, have a forest -> moved southwards

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20
Q

Plate tectonics

A

The study of the movement of the plates

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21
Q

Plate tectonics key points

A

When plates meet, they can slide past each other, diverge, or converge (mountains and ocean trenches)

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22
Q

Similar groups of animals

A

Llamas and camels - both domesticated animals, distant cousins

Kangaroos and cattle - fulfil a similar ecological role

African and indian elephants

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23
Q

Background extinction rate

A

The natural extinction rate of all species - around one species per million species per year

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24
Q

Mass extinction

A

Have been 5, there is an increasing rate of extinction due to climate change, natural disaster (volcanic eruption, meteorite impact)

Cretaceous-Tertiary (K-T extinction) where dinosaurs became extinct - around 65 million years ago

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25
Q

Holocene extinction event

A

The 6th mass extinction - we are currently undergoing it

Started at the end of the ice age around 9,000 to 13,000 years ago when large mammals such as the wooly mammoth and the sabre-toothed tiger became extinct (hunting)

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26
Q

Mass extinction patterns

A

Rate has accelerated in the last 100 years - biggest cause: HUMANS

Background rate was 1 per 200 years, but the past 400 years we have seen 89 mammalian extinctions - much more than the background rate

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27
Q

Living dead species

A

Species which have such small populations that there is little hope they will survive

They have lost a species that they depend upon (e.g. a pollinator insect for a flowering plant)

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28
Q

Causes of mass extinction (specifically K-T extinction)

A

Volcanic eruption, meteor impact putting huge amounts of dust into the atmosphere, climate change over a long period

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29
Q

The 5 mass extinctions - table

A

Now - Holocene

65 mya - Cretaceous-Tertiary (17% families and large dinosaurs lost)

199-214 mya End Triassic (23%, some vertebrates)

251 mya Permian-Triassic (95%, 54% of families)

364 mya Devonian (19% families)

440 mya Ordovician-Silurian (25% families)

30
Q

Weedy species

A

Organisms that do well in the environments we create, survive and thrive in the current mass extinction (urban rats, domesticated animals)

31
Q

6th mass extinction causes

A

Humans - direct cause of ecosystem stress because we:

  • Transform the environment (cities, roads, industry, agriculture)
  • Overexploit other species (fishing, hunting, harvesting)
  • Introduce alien species (may not have natural predators)
  • Pollute the environment (kill species directly/indirectly)
32
Q

Living Planet Report

A

Periodic report produced by the WWF on the state of the world’s ecosystems

Loss and degradation, decline in living planet index measure of ecosystem health) by 30%

Measures Earth’s biological diversity

33
Q

changes in biodiversity

A

Stage 1: modern humans spread over the earth, homo sapiens outcompeted Neanderthal man in Europe
hunting and extinction of wooly mammoths

Stage 2: humans became farmers 10,000 years ago
invention of agriculture meant that humans did not compete with other species in the same way for food
importing goods -> can exceed carrying capacity

34
Q

Total world biodiversity

A

7 million species, most are animals and terrestrial, 2/3 are in tropics (tropical rainforests), 50% of tropical rainforests have been cleared by humans

35
Q

Beetles (coleoptera)

A

Group with the most identified and named species

Have about 25% of all named species

36
Q

Current extinction rate

A

100 species per million species per year

37
Q

Hotspots

A

Species are not equally spread over the earth but highly concentrated in some areas

50% of all animals and plants are in 1/30 of the hotspots which make up only 2% of land

38
Q

Factors that help maintain biodiversity: complexity of the ecosystem

A

The more complex a food web is, the more resilient it is to the loss of one species or reduction in its population size

If 1 type of prey/predator is lost, the others will fill the gaps left

May not be good for species diversity though, as one species is lost completely but the community continues

39
Q

Factors that help maintain biodiversity: stage of succession

A

Plants and animals colonize a bare piece of land, species diversity increases, climax community is reached

Communities in young ecosystems that are undergoing succession may be more vulnerable than those in older ones which are more resilient and stable

40
Q

Factors that help maintain biodiversity: limiting factors

A

If the abiotic factors are in abundance, the system is more likely to manage if one is reduced

41
Q

Factors that help maintain biodiversity: inertia

A

Inertia is the property of an ecosystem to resist change when subjected to a disruptive force

Helps planners know which site will resist change or recover most quickly

42
Q

Natural hazards

A

Naturally occurring events that have a negative impact on the environment (and humans)

43
Q

Loss of habitat

A

Major cause of loss of biodiversity, small and large scale due to human activities

Habitat destruction or degradation occur when we develop or build on a piece of land

44
Q

Fragmentation of habitat

A

The process whereby a large area is divided up into a patchwork of fragments, separated from each other by roads, towns, factories, fences, power lines, pipelines or fields

Act as islands within an inhospitable sea of modified ecosystems

Invasion of habitat by pest species or humans increases, possibility - disease spreads

45
Q

Pollution

A

Caused by human activities - can degrade or destroy habitats and make them unsuitable to support the range of species that a pristine ecosystem can support

Local pollution (pesticides, oil spills); environmental pollution (emissions, transport); run-off of fertilizers into waterways; climate change

46
Q

Overexploitation

A

Human populations expand, technology has allowed us to get better at catching, hunting and harvesting

47
Q

Introducing non-native (exotic/alien) species

A

Can upset a natural ecosystem - humans have done this by the colonisation of countries, bringing their own crops/livestock

48
Q

Spread of disease

A

Decreases biodiversity - diseases of domesticated animals can spread to wild species and vice versa, particularly if population densities are high

49
Q

Modern agricultural practices

A

Reduce diversity with monocultures, genetic engineering and pesticides. Fewer are grown commercially and more pest species are removed

50
Q

Vulnerability of tropical rainforests

A

Decreasing due to human activity, ranching and logging commercially

51
Q

Shifting cultivation

A

A low density of human population is sustainable as they clear a small area of forest, grow crops for two or three years and then move on to the next as the soil is exhausted

52
Q

Why are rainforests rich in biodiversity

A

Ecological niches - high levels of heat, light and water - photosynthesis is rapid and not limited by the lack of raw materials, fast rate of respiration and decomposition

53
Q

What makes a species prone to extinction: narrow geographical range

A

If a species only lives in one place and the place is damaged or destroyed, the habitat is gone

54
Q

What makes a species prone to extinction: small population size or declining numbers

A

Small population has a smaller genetic diversity and is less resilient to change - cannot adapt as well

More inbreeding until populations are the ‘living dead’ or they become extinct

55
Q

What makes a species prone to extinction: low population densities and large territories

A

Habitat fragmentation can restrict its territory, and if there is not a large enough area left for each individual, they area less likely to survive as a species

56
Q

What makes a species prone to extinction: few populations of the species

A

If there are only 1 or 2 populations left then that is their only chance of survival

57
Q

What makes a species prone to extinction: a large body

A

Top predators are rare

58
Q

What makes a species prone to extinction: low reproductive potential

A

Reproducing slowly and infrequently means that the population takes a long time to recover

59
Q

What makes a species prone to extinction: seasonal migrants

A

Species that migrate have long migration routes, they need the habitats at the end of the migration route - it can’t be destroyed

60
Q

What makes a species prone to extinction: poor dispersers

A

Species that cannot move easily to new habitats

61
Q

What makes a species prone to extinction: specialized feeders or niche requirements

A

Eating only specific things; eg panda eating bamboo shoots

62
Q

What makes a species prone to extinction: edible to humans and herding together

A

Overhunting or over harvesting can eradicate a species, especially if they live in large groups (easier to exploit them at once)

Uses of body parts for medicine - tiger

63
Q

Island organisms

A

Vulnerable to extinction. island characteristics: small population; high degree of endemic species; genetic diversity is low; islands are vulnerable to non-native predators

64
Q

Dodo

A

Island species that became extinct

65
Q

IUCN (World Conservation Union)

A

Founded in 1948, mission is to influence, encourage and assist societies throughout the world to conserve the integrity and diversity of nature and to ensure that any use of natural resources is equitable and ecologically sustainable

66
Q

IUCN Red List

A

Monitors the state of the world’s species, determines the conservation status of a species

67
Q

Conservation biology

A

The sustainable use and management of natural resources

68
Q

Preservation biology

A

Attempts to exclude human activities in areas where humans have not yet encroached

69
Q

CITES

A

The Convention on International Trade in Endangered Species of Wild Fauna and Flora

70
Q

Ecotones

A

Where two habitats meet and there is a change near the boundary

IB Environmental Systems and Societies (4 decks)

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