BIOL 121 Lecture Notes - Lecture 9: Cambrian Explosion, Gene Duplication, Adaptive Radiation
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BIOL 121 Full Course Notes
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Document Summary
Evolution: great changes; diversity and divergence: mechanisms of change. Small changes appear as big changes: gene duplications and the. Hox genes are important in specifying morphological traits and in development (order and place) and are responsible for the 3d pattern of structures. Increased complexity of hox complex is related to the increased complexity of organisms. There are groups that branch off early (like jellyfish) that have fewer hox genes and simpler body plans. Conversely, groups that do not branch off early have more hox genes and more complex body plans. Also genes within a cluster are very similar which is perhaps due to duplication the whole hox cluster could have been duplicated twice to lead to vertebrates. Exception: crustaceans are complex but have only 5 hox genes. When gene duplication occurred, new hox genes were greated, b/c genes within the cluster are similar in structure and base sequence.
