Chapter 1: Extinction Flashcards
how is our age structure skewed?
skewed towards a large portion of young individuals
population momentum
age structure causing transient effect on population growth
human population growth & humans meet biodiversity
- not all age/stage classes are created equal
- not all species are created equal
not all age/stage classes are created equal
for people, deer, or salamanders: population growth is affected by distribution across stages
how is population growth affected across stages?
affected by distribution
not all species are created equal
- numbers, distributions
- per capita effects
humans have a ______ per capita effect
large
5 categories of anthropogenic stressors on wildlife
- conversion of land & sea
- overexploitation through harvest
- invasive species (including disease)
- pollution
- climate change
humans and extinction rates
- more species on earth now than ever before
- around 98% of the species that have evolved on earth over the past 3 billion years are now extinct
extinction as a process
natural & inevitable
are humans increasing extinction rates?
- extinction rates are higher
- contemporary humans caused extinction rate to be high enough to lead to a 6th mass extinction
5 mass extinctions
- Ordovician Silurian
- Late Devonian
- Permian Triassic
- Triassic Jurassic
- Cretaceous Palogene
mass extinction
a sharp spike in the rate of extinction of species caused by a catastrophic event or rapid environmental change
life span of a species
- average time from speciation to extinction
- expressed as a rate (E/MSY)
E/MSY
- # species extinction per million species per year
- # species extinction per 10,000 species per 100 years
