lecture19F06 - Lecture 19: Molecular evolution Readings:...

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Lecture 19: Molecular evolution Some needed terms homology, othologous, paralogous, alignment The Big Picture Trees again (oh no!) mutations occur in a tree-like sequence, outgroup analysis, convergence, parallelism, reversal, randomness Readings: Ch. 25.4, 25.5 The molecular clock the clock in microevolution, in macroevolution Jumping genes
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Figure 25.17 Two types of homologous genes Ancestral gene Speciation Orthologous genes Ancestral gene Gene duplication Paralogous genes (a) (b)
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Fig. 25.6 DNA sequences need to be aligned before we can deduce the homologous sites (a site is just a position in the sequence).
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TIME 1 2 3 7 4 11 10 11 15 14 18 16 20 21 9 12 13 17 19 22 23 24 Present The grand view of the combined effects of drift and mutation - new alleles arise by mutation, may go extinct immediately or increase. But all alleles go extinct eventually. Some point in the past
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.. C ATC C T.. ..AATCGT. . ..AATC C T.. ..AATCGT. . ..AATCGT. . ..AATC C T.. ..AATCGT. . ..AT T CGT. . ..AATC C T.. Mutation : adds new sequences (alleles) of genes in a tree-like pattern Normal replication “Abnormal” replication - mutation 1 2 3 4 Generation Evolution as it occurs
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.. C ATC C T.. ..AATCGT. . ..AATC C T.. ..AATCGT. . ..AATCGT. . ..AATC C T.. ..AATCGT. . ..AT T CGT. . ..AATC C T.. Parsimony : put the tree together so that each mutation occurs only once. Evolution as we estimate it - an allele phylogeny These belong on a branch because they share the derived C state at character 5
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A different hypothetical data set to show some more features of a parsimony tree. In this case, if we know which bases are derived and which are ancestral, it is child’s play to put together the parsimony tree. ATTAGAT TAGCGATCGCTTTAATGG GGTAG original ATTAGAT TAGCGATCGC A TTAATGG GGTAG mutant 1 ATTAGAT TAGCGATCGC A TTAAT C G GGTAG mutant 2 ATTAGAT A AGCGATCGC A TTAAT C G GGTAG mutant 3 T to A G to C T to A 3 evolutionary “steps”
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This note was uploaded on 04/07/2008 for the course IB 201 taught by Professor Hughes/berlocher during the Spring '07 term at University of Illinois at Urbana–Champaign.

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lecture19F06 - Lecture 19: Molecular evolution Readings:...

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