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5.2 extinctions and protecting species (Background extinctions (extinction…
5.2 extinctions and protecting species
Background extinctions
Evolution doesn't increase or decrease biodiversity
speciation increases biodiversity
extinction decreases biodiveristy
extinction is permanet
extirpation is a local extinction
background extinction isn't caused by humans
99.9% of all species that have ever existed are extinct. Usually species live for 2-10 million years
speciation rate is faster than extinction rate
there have been 5 mass extinctions throughout earths history
Ordovician
Devonian
Permian
Trissiac
Cretaceous
Mass extinctions can be caused by global warming and cooling, large changes in sea level and ocean water acidity, volcanic eruptions, large asteroids hitting the planet and competition from newly migrated species
human caused extinction
current extinction rates are way higher than background rates. Species are becoming extinct 100 times faster than prehuman times
Some species are more vulnerable to extinction because they don't breed frequently , they have a specific diet or habitat, live in small range, are rare, and commercially valuable
island species are more vulnerable because they are specialists
generalists are more likely to adapt to human dominated landscapes and some may even become pests
treaties and laws to protect species
establishing and enforcing environmental laws and international treaties can help protect species and ecological services
CITES (convention on international trade in endangered species of flora and fauna)
convention on biological diversity
the US endangered species act (ESA)
Protecting species ex Situ
Seedbanks and botanical gardens are used to preserve genetic information and the seeds of endangered plant species
wildlife farms: Breeding animals for commercial purposes, help reduce hinting in the wild, species can be released to boost wild populations
zoos and aquariums: Preserve some critically endangered animal species to one day reintroduce them to wild habitats