Key Area 7-Mass Extinction and Biodiversity Flashcards
What is a mass extinction?
Total wipeout of a species
What type of evidence suggests there have been several mass extinctions?
Fossil evidence
What happens to biodiversity after a mass extinction?
It reduces
Why are there difficulties estimating mass extinctions?
Only based on approximations
Only have fossils from birds and mammals
When did the mega fauna become extinct?
When humans came around
Why are current species extinction rates thought to be higher than expected?
Human activities
What are the three measurable components of biodiversity?
- genetic
- species
- ecosystem
What is genetic diversity?
Genetic variation (numbers and frequency of alleles) in a population
What happens to the genetic diversity if a population dies?
Decreases
What is species diversity?
The number of different species in an ecosystem and their abundance
What reduces species diversity?
If some species are more dominant than others
What is the species diversity like if an area is very isolated?
Lowers the species diversity
What happens to the species diversity if the habitat surface area is small
Low species diversity
What is ecosystem diversity?
The number of distinct ecosystems in an area
