BISC 102 Lecture Notes - Lecture 17: Phylogenetics, Ocean Current, Extinction Event
Document Summary
Reproductive isolation: reproducing within the certain portion of population that share a niche or trait speciation: angiosperms has lots of separate species because: Dependence on pollinators (mostly insect) when insects diversify, so do angiosperms and vice versa; co-evolution. Genome duplication: plants reproduce in large numbers one event of genome duplication of a mutant = large scale mutation in population natural selection adaptive radiation. Mass extinction: driven by global environmental causes, permian extinction (250 mya) 90% of all species gone (96% marine; 70% land) Siberian volcanic activity largest volcanic activity in last 500 mya. Formation of pangea loss of coastlines, change in ocean circulation pattern and ocean chemistry. Reduced oxygen in land and ocean by the 2 above: cretaceous extinction (65 mya) 60-80% of all species gone land animals most affected. Iridium layers (rare on earth, common in meteorites) indicate massive meteorite impact caused the extinction.