KEY CONCEPT Modern classification is based on evolutionary
KEY CONCEPT Modern classification is based on evolutionary relationships.
• Physical similarities are not always the result of close relationships. • Genetic similarities more accurately show evolutionary relationships.
Kingdom Phylum Class Order Family Genus Species PHYLOGENY n Biologists group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities. n Phylogeny = the study of evolutionary relationships among organisms.
Phylogenetic Tree
Phylogenetic trees are usually based on a combination of these lines of evidence: Fossil record Morphology (structure) Embryological patterns of development Chromosomes and DNA
Kingdom Phylum Class Order Family Genus Species PHYLOGENY n Classification q using Cladograms are diagrams that show the evolutionary relationships among a group of organisms.
Kingdom Phylum Class Order Family Genus Species PHYLOGENY Example of a cladogram A B C D E F Clade or lineage Speciation: formation of two new species from one T I M E
Kingdom Phylum Class Order Family Genus Species CLADOGRAMS This cladogram shows the evolutionary relationship among several vertebrates. Hagfish Fish Lizard Frog Mouse Pigeon Chimp Feathers Fur & Mammary Glands Lungs Jaws Claws or Nails
Kingdom Phylum Class Order Family Genus Species CLADOGRAM Hagfish Lizard Fish Mouse Pigeon Frog Chimp Feathers Lungs Claws or Nails Fur & Mammary Glands Jaws n Characteristics listed below the line are called derived characters (traits).
Kingdom Phylum Class Order Family Genus Species CLADOGRAM Hagfish Lizard Fish Mouse Pigeon Frog Chimp Feathers Do frogs hagfish have jaws? glands? mammary Lungs Claws or Nails Fur & Mammary Glands Jaws n When the derived character is above an organism, the organism lacks that derived character.
Kingdom Phylum Class Order Family Genus Species 3. CLADOGRAM Hagfish Lizard Fish Mouse Pigeon Frog Chimp Feathers Do pigeons lizards have claws have or nails? jaws? Lungs Claws or Nails Fur & Mammary Glands Jaws n When the derived character is below the organism, the organism possesses that derived character.
Primate Cladogram copyright cmassengale 12
The Dichotomous Key • Device for easily and quickly identifying an unknown organism. • The dichotomous key is the most widely used type in biological sciences. • The user is presented with a sequence of choices between two statements, couplets, based on characteristics of the organism. By always making the correct choice, the name of the organism will be revealed.
Dichotomous Keying • Used to identify organisms • Characteristics given in pairs • Read both characteristics and either go to another set of characteristics OR identify the organism copyright cmassengale 16
Example of Dichotomous Key 1 a 1 b 2 a 2 b 3 a 3 b 4 a 4 b Tentacles present – Go to 2 Tentacles absent – Go to 3 Eight Tentacles – Octopus More than 8 tentacles – 3 Tentacles hang down – go to 4 Tentacles upright–Sea Anemone Balloon-shaped body–Jellyfish Body NOT balloon-shaped - 5 copyright cmassengale 17
A. one pair of wings B. Two pairs of wings
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