Extinction Flashcards
What results in more species?
Higher rate of speciation
When is a species considered extinct?
When surveys have failed to detect it within its range.
How are extinction records biased?
They are biased towards flowering plants, birds, and mammals which are more conspicuous and better studied.
Why do marine species have lower extinction rates?
There is little fossil evidence therefore making it more difficult to establish extinctions.
What happens to extinction rates when the area reduces?
extinction rate rises above the baseline until a new equilibrium species richness is reached.
What are the causes of extinctions?
Selective harvesting - Removing a specific species from a habitat whilst leaving the habitat intact (E.g. Spix’s Macaw).
Introduced species
Competitors
Disease (e.g., chytrid fungus)
How do extinctions increase when habitat patches become smaller?
Smaller patches make it more accessible to humans.
How have humans affected marine megafauna such as Whales?
Subsidence whaling began in 3000 BC.
Industrial whaling began in the 17th Century with the introduction of factory ships in the 20th century.
Though this led to rapid depletion of whales there have been no extinctions (So far).
Whaling was made illegal globally in 1986, however, there are still some countries that practice whaling.
How many species of insects have gone extinct?
5-10% have likely gone extinct since the industrial age.
Only 5.5 million species and only 1/5th are named.
