Wiens-lecture 6-7April

Wiens-lecture 6-7April - Todays Lecture Finish molecular...

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Today’s Lecture • Finish molecular evolution • Introduction to phylogeny
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Molecular Evolution • Genome size varies widely among species; partly due to number of functional genes, but also amount of non-functional DNA
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Molecular Evolution • Gene duplication (evolution of one or more additional copies of a gene) is a key aspect of molecular evolution • Gene duplication can allow origin of new functions • One copy performs old function, while new copy can evolve new function • One copy may also evolve to become functionless pseudogene
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Molecular Evolution • When more than one copy of a gene is present in a genome, genes belong to same “gene family” • May be duplication of entire genome through polyploidization • Early vertebrates are thought to have gone through one or more rounds of polyploidization • Many genes in vertebrates belong to gene families with four copies; may be important part of our complexity!
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Molecular Evolution • “duplication and individualization” is an important principle for creating diversity in evolution • Applies to morphology (phenotype) as well as genes; duplicate a structure, let one version diverge while the other keeps its old function • Mammals differ from other vertebrates in having teeth with different structure and function • What other examples are there on your body?
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Introduction to Phylogeny Phylogeny = history of evolutionary branching and descent (family tree) Systematics = branch of biology dedicated to reconstructing phylogeny (also called “phylogenetics”)
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Answers the question: What is it? Why phylogeny is important
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Why phylogeny is important? Phylogenies are necessary to tell us what evolutionary changes have occurred. group of 8 species: 4 species have a trait, 4 do not What happened? Did the trait evolve once? Did it evolve 4 times? Was it lost 4 times?
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Phylogenies tell us: what happened? Evolution of male display ornaments. Major question in evolutionary biology: what explains the origin of elaborate male ornaments? peacock stalk-eyed fly
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Phylogenies tell us: what happened? Evolution of male display ornaments. Phylogenies show that in many groups ornaments are lost 4-5 times more often than gained present lost
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Introduction to Phylogeny Why phylogeny is important • Phylogeny answers the question “what is it?” Is a whale a mammal or a fish? Emerging diseases: what is H1N1?
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Wiens-lecture 6-7April - Todays Lecture Finish molecular...

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