Key Concepts in biocon

Question 1

What are the main threats to biodiversity?

Answer 1

Habitat destruction
Overexploitation
Invasive species
Pollution
Climate change
Multiple interacting threats

Question 2

Give an example of a mammal that has been overexploited

Answer 2

Steller’s sea cow - discovered by Europeans in 1741 and became extinct 27 years later
Relative of manatees
Valuable to humans - food, skin used to make boats, fat used for food and oil lamps
Easy to capture

Question 3

Give an example of a bird that has been overexploited

Answer 3

Passenger pigeon
Once the most abundant bird in N.America and possibly the world
Slow decline recorded 1800-1870 and catastrophic decline 1870-1890 (railways and telegraph allowed commercialisation)
Extinct by 1914
Valuable to humans - food (for poor and slaves), sport
A contributing cause was deforestation in their breeding grounds

Question 4

Give an example of a current overexploitation problem

Answer 4

Fish - highly nutritious food - 5-25% of dietary protein to humans
Went from catching 21m/t/yr to 109m/t/yr from 1950-1994
In 1900 oceans contained 6x more fish than in 2009
Species at risk of extinction - generally those with long lifespan and old age of reproductive maturity eg. bluefin tuna, hake, halibut
Marine environment is difficult to regulate due to international boundaries and migratory species

Question 5

Give 2 examples of fish that have had drastic population crashes

Answer 5

Peruvian anchovy - 1970 - 11 million tonnes (94% of worlds catch) 1980 - 1.2 million tonnes
Canadian Newfoundland cod - 1968 800,000 tonnes 1992- 8000 tonnes

Question 6

Give examples of birds that have been effected by DDT and give a reason it is still in use in developing countries

Answer 6

Brown pelicans in N.America
Peregrine falcons in N.America, Canada and UK
Kestrels in UK
Effective malaria prevention

Question 7

Give an example of an invasive species

Answer 7

Black rat - native to Asia but has now spread across the world via ships
Has directly caused or contributed to many species of wildlife going extinct including birds, small mammals, reptiles, invertebrates and plants especially on islands
Omnivourous
Prey on eggs of young forest bbirds

Question 8

Why are coral reefs important and how is climate change affecting them?

Answer 8

Extremely important for biodiversity - habitat for over 25% of marine life
- provide nurseries for many commercially important fish
- vital for people and business, protecting coastal areas from storm waves and bringing in large amounts of tourism
Temperature increase - heat affects the algae that live symbiotically with the corals that supply them with food
- heat stress damages algae and leads to coral death
- this is called bleaching
Ocean acidification - Oceans have absorbed half of the CO2 produced by burning fossil fuels decreasing pH
- At lower pH corals cannot absorb calcium carbonate they need to maintain their skeletons
The ocean is about 30% more acidic now than it was in 1751

Question 9

What factors caused the extinction of the dodo?

Answer 9

Earliest recorded extinction event caused by humans
- first sighting in 1598 last in 1662
Easy prey for sailers due to their lack of fear and inability to fly
Introduced species - pigs and macaques in particular
Habitat destruction, deforestation

Question 10

What factors led to the extinction of the golden toad?

Answer 10

Endemic to Costa Rica - extinct since ~1989

• el nino warming
• fungus
• invasive species
• pollution
• climate change

Question 11

In descending order list the organisms most endangered

Answer 11

Amphibians
Mammals
Birds
Reptiles
Fish
Plants
Mollusks
Insects

Question 12

How do humans benefit from biodiversity in terms of medicine?

Answer 12

Most plants produce secondary compounds which are toxins used to protect them from insects and other animals which eat them but some work as medication
- examples include morphine, cocaine, caffeine and nicotine
Antibiotics are largely derived from fungi and bacteria
Animal venoms and poisons have excited intense research for their medical potential
- deathstalker venom “chlorotoxin” attaches to specific brain cancer cells allowing surgeons to differentiate cancer cells from healthy cells

Question 13

How do humans benefit from biodiversity through agriculture?

Answer 13

Different crops do well in different conditions
Disease resistance
New crop varieties are bred from different species
New breeds must be continually grown to keep up with existing pest organisms
Seed banks preserve biodiversity

Question 14

When were the 5 mass extinction events?

Answer 14

end-ordovician - 450mya
end-devonian - 375mya
end-permian - 250mya
end-triassic - 200mya
end-cretaceous - 60mya