BIO SCI 94 Lecture Notes - Lecture 7: Ordovician, Holocene Extinction, Cambrian Explosion

• School: UC-Irvine
• Department: Biological Sciences
• Course: BIO SCI 94
• Professor: Robin Bush

Document Summary

Lecture 7: phylogenies and the history of life. Producing many descendent species with a wide range of adaptive forms. What does a clade look like if it underwent an adaptive radiation: the species involved form a monophyletic group, speciation occurred relatively rapidly compared with other groups, the species diversified ecologically. Morphological innovations: morphological trait that makes it possible to exploit resources in a new way or occupy new habitats, new niches. Tremendous increase in the size and morphological complexity of animals: accompanied by diversification in how they made a living. Triggers: higher oxygen levels, evolution of predation, new niches beget more new niches, new genes and new bodies. Class of genes found in several animal phyla. Expressed in distinctive pattern along the anterior posterior axis in early embryos. Rapid extinction of a large number of lineages scattered throughout the tree of life. Many scientists propose that life on earth is on the verge of the sixth mass extinction.