BIOL 1001 Lecture Notes - Lecture 27: Speciation
18 Jan 2016
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Adaptive radiations & mass extinctions the end-permian extinction: 250 mya, dec 11th the end-cretaceous extinction, 65 mya, dec 26th, extinction of the dinosaurs, k-p the end-cretaceous-paleocene boundary. Iridium is common in asteroids : but not in most earth geological formations. Recovery after the cretaceous: initially, terrestrial ecosystems around the world were radically simplified, and the marine diversity remained low for 4-8 million years, mammals diversified. Left empty by the extinction of the dinosaurs: within 10-15 mya . All the major mammal orders living today had appeared. Phylogenetic trees: star phylogenies = a large phylogenies = polytomies in, rapid speciation, adaptive radiations represent speciation events which are so rapid . Therefore, the order of branching cannot be resolved. If rapid speciation in a single lineage is followed by divergence into many different adaptive forms .
