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Phylogeny & Systematics Chapter 25
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Phylogeny: the evolutionary history of a species
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Systematics: the study of biological diversity in an evolutionary context Analytical approach Focuses on morphological, biochemical and molecular resemblances Constructing a Phylogeny:
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The fossil record: the ordered array of fossil, within layers (strata) of sedimentary rock Constructing a Phylogeny:
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Sedimentary rock(?) : Richest source of fossils Lake Turkana Boy(1984) The fossil record
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Limitations? The fossil record
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Morphological and Molecular Homologies: Homologies= similarities do to shared ancestry Constructing a Phylogeny:
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Homology vs. analogy Convergent(independent) evolution vs shared ancestry Similar environmental pressures can produce analogous adaptations in organisms from different lineages Some more challenges:
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The tracing of evolutionary relationships (phylogenetic tree) Linnaeus(taxonomy) Binomial Nomenclature Phylogenetics
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Binomial Nomenclature-two part naming system First part: genus(genera) Second part: species(specific epithet) Phylogenetics
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Hierarchical Classification:
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1. Domain 2. Kingdom 3. Phylum 4. Class 5. Order 6. Family 7. Genus 8. Specie s Hierarchical Classification
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1. Eukarya 2. Animalia 3. Chordata 4. Mammalia 5. Primate 6. Homidae 7. Homo 8. sapiens Example:
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Classification is reflected in the branching of the phylogenic trees Evolutionary relationships are traced between some of the taxa What is the connection between classification and phylogeny:
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Cladograms: diagrams that show patterns of shared characteristics Clade: a group of species that includes an anestral species and all its descendants. Phylogenetic systematics:
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Cladistics: the analysis of how species may be grouped into clades Phylogenetic Trees
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Monophyletic- single ancestor that gives rise to all species in that taxon and to no species in any other taxon The only valid clade(cladogram) Valid vs. non valid clades
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Paraphyletic- lacks information about some species Consists of an ancestral species but not all descendants Not valid Valid vs. non valid clades
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Polyphyletic-grouping of several species that lack a common ancestor Not valid Valid vs. non valid clades
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{ A Cladogram
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http://ccl.northwestern.edu/simevolution/obonu/cladograms/Open- This-File.swf http://ccl.northwestern.edu/ simevolution/obonu/cladog rams/Open-This-File.swf http://ccl.northwestern.edu/ simevolution/obonu/cladog rams/Open-This-File.swf http://ccl.northwestern.edu/ simevolution/obonu/cladog rams/Open-This-File.swf
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