Lecture 16 Flashcards
(15 cards)
What is extirpation?
The disappearance of a population of a species from a local area, while the species still exists elsewhere.
Why does extinction happen?
Environmental change occurs too quickly for adaptation.
Death rate exceeds birth rate (r < 0), causing population decline.
What is the IUCN?
a global system to classify species’
extinction risk.
What are the 3 main IUCN threat categories?
Critically Endangered - ≥50% chance of extinction within 10 years or 3 generations.
2. Endangered - 20% chance within 20 years or 5
generations.
3. Vulnerable - ≥10% chance within 100 years.
What is the Red List?
A comprehensive global inventory of threatened species-over 26,000 listed as at risk.
What is the Precautionary Principle in conservation?
Lack of complete scientific certainty shouldn’t delay conservation efforts when serious harm is likely.
What is background extinction?
Normal rate of species loss over time due to natural processes.
What is mass extinction?
The sudden loss of a large number of species due to natural catastrophes.
What is anthropogenic mass extinction?
Large-scale species extinction caused by human activities (e.g., pollution, overharvesting).
How does current extinction rate compare to historical levels?
Present rate is ~1000x higher than background levels-comparable to past mass extinctions.
What are the 4 main causes of current mass extinction?
- Habitat Loss
- Global Warming
- Introduced Species
- Overexploitation (Harvesting)
What is an example of habitat loss in marine ecosystems?
Trawling (marine “clearcutting”).
How does global warming lead to extinction?
Species may be unable to survive if conditions shift outside their tolerance range (limited phenotypic plasticity).
What are the impacts of zebra mussels?
Foul native clams
* Compete for food
* Cause extinction via competitive exclusion
The Earth is undergoing _____ extinction at a
_ times the background rate.
Anthropogenic, 1000x
