BIOLOGY 1M03 Lecture Notes - Lecture 14: Hox Gene, Gene Duplication, Cambrian Explosion
15 May 2017
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Document Summary
Hox gene, evo-devo, gene duplications, dating methods and diversification. Some researchers predicted a strong association between the order in which animal lineages appeared during evolutionary history. The number of hox genes present in each lineage and each lineage"s morphological complexity and body size. The logic behind this new genes, new bodies hypothesis was that existing homeotic genes could have been duplicated before and during the cambrian explosion, producing new body plans and appendages. The number of genes in the hox cluster appears to have expanded in some groups (like vertebras) during the course of evolution. But clearly this is not the only cause for morphological diversification. Insects for example are extraordinarily diverse morphologically but have less. Both duplication of hox genes and changes in expression and function of existing genes have been important in the elaboration of animal body plans. Sponge and jellyfish hox homologs do not have temporal, spatial or quantitative co-linearity.
