cladograms and dichotomous keys
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Cladograms and Dichotomous Keys. Taxons. Most genera contain a number of similar species The genus Homo is an exception (only contains modern humans) Classification is based on evolutionary relationships. Basis for Modern Taxonomy. - PowerPoint PPT PresentationTRANSCRIPT
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Cladograms and Cladograms and Dichotomous Dichotomous
KeysKeys
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TaxonsTaxons•Most Most generagenera contain a contain a
number of similar speciesnumber of similar species•The genus The genus HomoHomo is an is an
exception (only contains exception (only contains modern humans)modern humans)•Classification is based
on evolutionary evolutionary relationshipsrelationships
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Basis for Modern Basis for Modern TaxonomyTaxonomy•Homologous structuresHomologous structures
(same structure, different (same structure, different function)function)•Similar Similar embryoembryo
developmentdevelopment•Molecular SimilarityMolecular Similarity in in
DNADNA, , RNARNA, or , or amino acidamino acid sequence of Proteinssequence of Proteins
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Homologous Structures (BONES in the FORELIMBS) Homologous Structures (BONES in the FORELIMBS) shows Similarities in mammals.shows Similarities in mammals.
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Similarities in Vertebrate Similarities in Vertebrate EmbryosEmbryos
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CladogramCladogramDiagram showing how organisms are related Diagram showing how organisms are related
based on based on shared, derived characteristicsshared, derived characteristics such as feathers, hair, or scalessuch as feathers, hair, or scales
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Primate Primate CladogramCladogram
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Dichotomous KeyingDichotomous Keying•Used to identify Used to identify
organismsorganisms•Characteristics given in Characteristics given in
pairspairs•Read both Read both
characteristicscharacteristics and and either go to another set either go to another set of characteristics of characteristics OROR identify the organismidentify the organism
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Example of Dichotomous Example of Dichotomous KeyKey
1a Tentacles present – Go to 21a Tentacles present – Go to 21b Tentacles absent – Go to 31b Tentacles absent – Go to 32a Eight Tentacles – Octopus2a Eight Tentacles – Octopus2b More than 8 tentacles – 32b More than 8 tentacles – 33a Tentacles hang down – go to 3a Tentacles hang down – go to 443b Tentacles upright–Sea 3b Tentacles upright–Sea AnemoneAnemone4a Balloon-shaped body–4a Balloon-shaped body–JellyfishJellyfish4b Body NOT balloon-shaped - 54b Body NOT balloon-shaped - 5
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