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Classification. Chapter 18. How are living things classified? What traits do biologists use to classify? What schemes do scientists use to organize their knowledge of living things and evolutionary relationships?.
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Classification Chapter 18 • How are living things classified? • What traits do biologists use to classify? • What schemes do scientists use to organize their knowledge of living things • and evolutionary relationships? http://nanopatentsandinnovations.blogspot.com/2011/12/top-10-new-species-for-2011.html
Inquiry Lab What is your system? Directions: • Examine the assortment of objects provided. • Sort objects into groups of related objects. Try to get every object into a group with at least one other object. • Choose a name for each group. • Choose one object from your collection and trade it with another group. • Try to fit the new object into one of your groups.
The Importance of Classification In order to study and use living things, we need a name for each. This avoids confusion from scientists around the world. Taxonomy: the practice of describing, naming, and classifying organisms. Biologists group organisms into large categories as well as smaller more specific categories= taxon.
-Provides consistence-Common names not always the best - More than one common name, ex Robin/Robin in Great Britain - Advantage is to provide scientific naming system that biologist can communicate regardless of native language. North American Robin Great Britain Robin
Levels of Classification • 7 different levels of organization, (from largest to smallest) • Kingdom • Phylum • Class • Order • Family • Genus • Species King Philip Came Over For Graduation Speeches
Carl Linnaeus • 1750’s • Swedish biologist • Cataloged all known species and added a two word Latin name for each species= Binomial nomenclature or scientific name • No two species have the same scientific name
Scientific Names Can you predict the common name? Carnegiea gigantea
Canis familiaris Felis catus
Scientific Name Rules • All members of same genus share the genus name as the first term. • Second term is the species identifier and is often descriptive. • Capitalize genus name. • Species name is lowercase. • Both terms should be italicized. EX: Homo sapiens, Felis domesticus
Latrodectus variolus Black widow Danaus plexippus Monarch butterfly
Rana pipensLeopard frog Pseudacris cruciferSpring peeper frog
Chrysemys picta Painted Turtle Terrapene carolina Eastern Box Turtle
Thamnophis sauritus Ribbon Snake Lampropeltis triangulum Milk Snake
Tamias striatus Eastern chipmunk Mephitis mephitis Striped Skunk
Procyon lotor Raccoon Didelphis virginiana Opossum
Micropterus salmides Largemouth bass Perca flavescens Perch
Other Michigan Organisms…. This list presents the Endangered (E), Threatened (T), and Probably Extirpated (X) animal species of Michigan, which are protected under the Endangered Species Act of the State of Michigan. http://mnfi.anr.msu.edu/data/specialanimals.cfm
Homo sapiens Human
Review Why do biologists have a system for naming and grouping living things? What are the rules for scientific names? List the categories of the Linnaean system from largest to smallest.
Modern Systematics It shows an organisms relationship to other organisms and their evolutionary history. Systematics: a field of expertise where scientists identify one species from another. Extinct theropod dinosaur Cassowary modern bird
Old thinking… (based on physical similarities) Dinosaurs were reptiles. Bird were NOT reptiles but in own group. New thinking … (based on new technology: DNA, proteins, embryo development, fossils) Birds evolved from dinosaurs.
Dolphin Whale Fish!
Systematics Old thinking… Dolphins and whales different than fish. New thinking… Whales related to early land mammals.
Phylogenetics Drawing a family tree that links ancestors from thousands to millions of generations. • NOT just based on physical similarities, which can be misleading • Based on fossil evidence, bone structure, DNA, proteins, embryo development Insect Wing Bird Wing
Cladistics An objective way to sort out relatedness; look for characteristics that are shared between groups because of common ancestry. Cladogram: a phylogenetic tree drawn in a specific way to show a comparison of characters among several groups Flowers are a derived character shared only with flowering plants. Seeds are a derived character shared between conifers and flowering plants.
Modern Systematics • Cladistics 1. Model used to represent evolutionary history among species 2. Used to determine the sequence in which different groups of organisms evolved
Dichotomous Keys • Dichotomous Keys are used to identify unknown species based on classification characteristics. • Pairs of descriptions that lead to the identification of an object.
Lab:Using the fish key, identify the following Michigan fish.*=Numbers that are circled DO NOT have a body covered with scales!(#’s 1,2,6, 8, 11, 14, & 17)
Dichotomous Key- Shoes • Need 10 students to each volunteer a shoe to use for “shoe collection” • Study the structure and organization of a dichotomous key as a model for this activity • As a class, work to design a new dichotomous key for the “shoe collection” • Be sure that each part of key leads to either a definite identification of a shoe’s owner or another set of possibilities. Be sure that every shoe is included. • Test the key using each shoe in the collection
Review What are some problems that arise when we only group based of physical similarities? How do you make a cladogram? Identify kinds of evidence used to infer relatedness.
Kingdoms and Domains Classification systems change when scientists learn new information. 1700’s: Linnaeus, Plant and Animal Kingdoms 1800’s: All one-celled life grouped together until biologists noticed prokaryotic (kingdom Monera) and eukaryotic cells (kingdom Protista). Sponges used to be grouped with plants, but with the invention of microscopes, they are grouped with animals due to cell structure. Kingdom Monera Kingdom protista
1950’s: Kingdom Fungi added 1990’s: Split Kingdom Monera into Kingdom Eubacteria and Kingdom Archaebacteria based on genetics Plant cell walls made of cellulose… fungi cell walls made of chitin 6 Kingdom System
3 Domain System… This is used along with 6 Kingdom System because scientists see differences among Prokaryotes AND similarities between all Eukaryotes.
Review How have biologists changed the Linnaean System over time? What are the 6 Kingdoms that align with the 3 Domains? List major characteristics of each Kingdom.