BIOL10001 Lecture Notes - Lecture 35: Soil Fertility, Siltation, Overexploitation
18 Oct 2018
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Document Summary
42% of extant species are threatened (best estimate) Most extinctions still occur primarily between mass events eg. megafauna constant extinction. Gone extinct more recently than previous mass extinction. Current extinction rate is 17-377 x background rate (over last 65 million years) History shows organisms with a larger body mass have a higher frequency of extinction. Australia"s extinction records are the worst in the world. 27 mammals, 22 birds, 4 frogs, 1 sh, 1 earthworm, 60 vascular plants have gone extinct in last. 1/3 of mammals species from deserts are now extinct. 50 plants species threatened per million people in australia. 4. 6 mammals species threatened per million people in australia less than 20 in usa, brazil, canada less than 0. 4 in usa, brazil, canada. When so few individuals of a specie remains, it no longer performs its previous functions or interactions. The time lag between habitat disturbance and extinction of species in that habitat.
