Lecture 24 _March 9_ Phylogenetics post

Lecture 24 _March 9_ Phylogenetics post - 3/8/11 Biology...

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3/8/11 1 Lecture 24: Wednesday March 9, 2011 Biology 171 Phylogenetics, Systematics, and the Tree of Life Announcements This Week in Discussion: Computer simulations of HWE Text Reading Chapter 27 (474-479) Important Definitions The Tools of Systematics Types of Phylogenetic Tree How to Build a Tree Uses of Phylogenetic Trees Why We Care • Naming and identifying species is important – we need to know how to recognize the species that are important to us (food, fiber, medicine, disease agents) • But if we know how these species are related to one another, we can also understand their evolutionary history and recognize the traits (useful or dangerous) that they have in common Some Definitions • Taxonomy – the identification and naming of organisms (= classification ) • Taxon – the name given to a particular group of organisms • Phylogeny – the evolutionary relationships among taxonomic groups • Systematics – the use of analytical tools to classify organisms and to build phylogenies • Clade – a group of organisms that includes the ancestral taxon and ALL of its descendants Phylogenetic Systematics The science that connects classification (taxonomy) with evolutionary history
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3/8/11 2 The Tools Of Systematics • The fossil record • Morphological homology • Molecular homology Tool 1. The Fossil Record More than 100 Million Years Old (Brazil) Caught Live in UK, 1980s Conclusion: Living dragonflies have strong evolutionary ties with very old taxa Tool 2. Morphological Homology
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3/8/11 3 Tool 2. Morphological Homology Tool 2. Morphological Homology Tool 3. Molecular Homology Ancestral Gene Homologous Genes Speciation Genetic Similarity Between 2 Species Suggests Recent Common Ancestor Tool 3. Molecular Homology • 14% of amino acids are identical across vertebrate hemoglobins and have remained unchanged since the evolution of the clade
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3/8/11 4 Danger! We can get tricked when traits look the same because of Convergent Evolution When two traits appear similar, but are not related by common ancestry, we call them either: Analogous traits (opposite of homologous) Or Homoplasies More Definitions
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Lecture 24 _March 9_ Phylogenetics post - 3/8/11 Biology...

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