3.3 Threats to biodiversity

Question 1

Why might the rate of loss of biodiversity vary between different countries?

Answer 1

• The ecosystems present in that country
• Protection policies and legislation in place
• Effectiveness of monitoring
• Environmental viewpoints of the population
• Stage of economic development

Question 2

What is an “extinction’?

Answer 2

Permanent loss of all members of a species
eg. dodo

Question 3

Extinction is n________

Answer 3

• natural phenomenon
• major catastrophes
• species are unable to adapt quickly enough to a natural environmental change
• 5 major extinction events so far

Question 4

What are some natural causes of extinction?

Answer 4

• Tectonic events
• Volcanic events
• Ocean temperature change
• Sea level changes
• Meteorite impact
• Glaciations

Question 5

What are some human causes of extinction?

Answer 5

• Habitat destruction
• Introduction of non-native species
• Population growth in humans
• Pollution
• Over exploitation of resources

Question 6

What is the “rate of extinction”?

Answer 6

“Number of species becoming extinct per unit time”
- Fossil records can reveal the average “lifetimes” of species

Question 7

What are the 5 mass extinction events?

Answer 7

1. End of Ordovician
2. Late Devonian
3. End of Permian
4. End of Triassic
5. End of Cretaceous

(All “END OF” except “LATE” Devonian!)
ODPTC

Question 8

What was the “End of Ordovician”?

Answer 8

• Mass glaciation
• 440M years ago
• 85% of species wiped out

Question 9

What was the “Late Devonian”?

Answer 9

• Global cooling
• 365M years ago
• 75% of Marine species lost

Question 10

What was the “End of Permian”?

Answer 10

• Volcanism and global warming
• 251M years ago
• 96% of all species extinct

Question 11

What was the “End of Cretaceous”?

Answer 11

• Meteor strikes
• Less than 1M years ago
• 75-80% of all species went extinct
• DINO DIED HERE!!!

Question 12

What are some of the impacst of humans?

Answer 12

• Previous extinctions due to physical causes over long timespans.
• Current mass extinction due to biotic cause (humans) and is accelerating.
• Humans are the direct cause because:
  –> transform environments, overexploit other species, introduce non-native species, pollute the environment

Question 13

What are some characteristics of threatened species?

Answer 13

• Low numbers
• Extremely specialized species
• Low reproductive potential
• Species that require large territories
• Species with limited dispersal ability
• Limited distribution
• Migratory species
• Species that are economically valuable
• Species that are vulnerable to pollution

Question 14

What is the definition of “stability of an ecosystem”?

Answer 14

“An ecosystem’s capacity to survive change may depend on diversity, resilience and inertia”

Question 15

What does the IUCN RED list hold?

Answer 15

The IUCN red list measures pressures on species

The main function is to pull together all information regarding species.
The data is gathered scientifically on a global scale and species are categorized according to their relative damage of extinction

Question 16

What are some factors which are used to determine a species conservation status?

Answer 16

1. Population size
   (Smaller populations are more likely to become extinct)
2. Degree of specialization
   (The more specialized a species is, the more prone to extinction they are)
3. Distribution
   (Species that live in a smaller area are under greater threat)
4. Reproductive potential and behavior
   (Low rates of reproduction = vulnerable)
5. Geographic range
   (Species with a limited geographic range may be under greater threat)
6. Degree of fragmentation
7. Quality of habitat
   (If the habitat becomes degraded then there is less available food!)
8. Trophic level
   (Species at a high trophic level, the top carnivores, are more prone to extinction)