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36 Cards in this Set

  • Front
  • Back

Extinction-level events (2 major)

Permain-Triassic (PTr)

Crestaceous-Tertiary (KT)

Permian-Triassic extinction event


Siberian volcanism - releases methane hydrate

runaway greenhouse effect

up to 95% species extinction

Cretaceous-Tertiary extinction


atmospheric particles - decreased sunlight and photosynthesis

up to 75% species extinction

6 major threats to biodiversity

human population growth


habitat destruction


species invasions

climate change

human population has experience ______ growth


Late Pleistocene extinctions

Large herbivores disappeared from America, Europe and Australia

All >1000kg

75% 100-1000kg

41% 5-100kg

<2% <5kg

Late pleistocene extinctions coincided with...

arrival of human hunters

Positive side for human population growth

it is slowing and will likely end this century

population size is dropping in many industrialized countries

education is a major driver of declining birth rates

Exploiations examples

bluefin tuna

Billfish: swordfish and marlin

extinction risk is related to...

generation length and value

destructive exploitation - methods

deep-sea trawling

cyanide and dynamite fishing

bushmeat trate

clearcut logging

Positive side of exploitation

tropical countries have largely restricted overhunting on land

some pops recovering due to conservation and management measures

destructive forms of exploitation are being increasingly limited or banned

consumer awareness is increasing

Habitat destruction: caused by


intensive agriculture

urban sprawl

extent of forest loss by continent

Russia and Europe has most forest cover

Asia has next with the most cleared

North and Central America has 3rd

___% of population within 100km of coast


Coastal habitat destruction - by




harbors, jetties

mass tourism


Seafloor habitat loss


Case study: palm oil plantations

15 million hectares worldwide

demand expected to double by 2020

used in food and industry

high-yielding biofuel

consequences of habitat loss

fewer habitats - fewer species

reproduction impaired if spawning or juvenile habitat is destroyed

changes in local climate

increased erosion

on the positive side for habitat loss

foest cover is increasing again in Europe and US

wetlands are now being restored

protection of critical habitat is becoming a cornerstone of conservation

Pollution: types




noise and light

Toxic pollution: examples

hydrocarbons, tar

heavy metals

acid rain

organochlorines (DDT, PCB, dioxin etc.)

toxic algal blooms

Nutrient pollution: examples

increase in nitrate, ammonium and phosphate from (sewage, agri- and aquaculture, erosion)

cause algal blooms, hypoxia, species- and habitat loss

Plastic pollution: examples

plastic debris in ocean - up to 100 000 items per km2 on ocean surface

microplastic particles are a new and emerging threat

plastic pollution: dangers



vector for other pollutants and invasive species

Noise and light pollution: examples

ship noise impairs whale communication

light pollution misleads turtle hatchlings

Postive side to pollution

major persistent pollutants such as DDT, PCB, leaded gasoline are banned and decreasing in environment

sulphur emissions and lake acidification have decreased through cap and trade

nutrient pollution is being reduced through sewage treatment

Species invasion:

biological invasion definition

the occur when a novel species enters a community for the first time

species invasions can be due to...

natural and human introductions

what kind of invasions have been particularly destructive and where?

predator and pathogen invasions especially on islands


New Zealand endangered birds surviving on a predator-free island

Example in the black sea

Jellyfish invade - fisheries crashed

positive side of invasive species

being removed from many islands

some invasive species can also be beneficial to ecosystems

stricter regulations on ballast water are implemented - research at dal

As human populations grow ...

overexploitation, habitat destruction, pollution and species invasions became severe threats to biodiversity

Extinction rates today are ....

100 - 1000X higher than pre-human (uncertain)

dominant threat in this century?

might by climate change