Chapter 27 Phylogenies and the History of Life 27.1 Tools for studying history: Phylogenetic trees 27.2 Tolls: Fossil record 27.3 Cambrian explosion 27.4 Adaptative radiations 27.5 Mass extinctions tolweb.org/tree/home.pages/aboutoverview.html Tree of Life Know approximate times for key early events indicated by arrows Note: dates from Campbell, not from Freeman! Fig 27.8 4.6 bya 3.7 bya 3.2 bya 2.1 bya 1.5 bya 540 mya The History of the Earth in One Year Fig 27.9 The Cambrian species explosion ~540 mya 27.11 Adaptive radiations Fig 27.12 Fig 27.14 Mass extinctions End of Cretaceous extinction 6 th major extinction of all time 50 percent of the world?s flora and fauna could be on a path to extinction within a hundred years---- And everything is affected: fish, birds, insects, plants, and mammals. By one count 11% of birds are on the edge of extinction; it?s doubtful that the majority of these will live much beyond the end of the next century. One in eight plants is at risk of becoming extinct. It is a worldwide epidemic of extinctions Our phylogenetic tree? What factors promoted speciation? 400,000 years ago 100,000 years ago Scott Freeman Biological Science 2/e
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