Chapter 18 - Classification Lesson Overview Chapter 18 - Classification

Assigning Scientific Names The first step in understanding and studying diversity is to describe and name each species. By using a scientific name, biologists can be sure that they are discussing the same organism. Common names can be confusing because they vary among languages and from place to place.

Binomial Nomenclature In the 1730s, Swedish botanist Carolus Linnaeus developed a two-word naming system called binomial nomenclature. The scientific name usually is Latin. It is written in italics. The first word begins with a capital letter, and the second word is lowercased. ex. Homo sapiens

Binomial Nomenclature The polar bear, for example, is called Ursus maritimus. The first part of the name—Ursus—is the genus to which the organism belongs. A genus is a group of similar species. The genus Ursus contains five other species of bears, including Ursus arctos, the brown bear or grizzly bear. The second part of a scientific name—maritimus for polar bears—is unique to each species and is often a description of the organism’s habitat or of an important trait. The Latin word maritimus refers to the sea: polar bears often live on pack ice that floats in the sea.

Linnaean Classification System Linnaeus also developed a classification system that organized species into a hierarchy, or ranking. In deciding how to place organisms into larger groups, Linnaeus grouped species according to anatomical similarities and differences(morphology).

Seven Levels 1. Kingdom: the largest and most inclusive of Linnaeus’s taxonomic categories 2. Phylum: classes are grouped includes organisms that are different but that share important characteristics 3. Class: closely related orders are grouped into the next larger rank 4. Order: closely related families are grouped into the next larger rank 5. Family: genera that share many similarities are grouped into a larger category 6. Genus: is a group of similar species 7. Species: individual organism

Camel Classification Species: Camelus bactrianus Genus: Camelus Family: Camelidae Order: Artiodactyla Class: Mammalia Phylum: Chordata Kingdom: Animalia

Evolutionary Classification The concept of descent with modification led to phylogeny—the study of how living and extinct organisms are related to one another. A clade is a group of species that includes a single common ancestor and all descendants of that ancestor—living and extinct. Cladograms This information is used to link clades together into a cladogram, which illustrates how groups of organisms are related to one another by showing how evolutionary lines, or lineages, branched off from common ancestors. Clades

Building Cladograms This cladogram represents current hypotheses about evolutionary relationships among vertebrates. Note that in terms of ancestry, amphibians are more closely related to mammals than they are to ray-finned fish!

Constructing a Cladogram 1 Identify the organism in the table that is least closely related to the others. 2 Use the information in the table to construct a cladogram of these animals. Analyze and Conclude 1. Interpret Tables What trait separates the least closely related animal from the other animals? 2. Apply Concepts Do you have enough information to determine where a frog should be placed on the cladogram? Explain your answer. 3. Draw Conclusions Does your cladogram indicate that lizards and humans share a more recent common ancestor than either does with an earthworm? Explain your answer. Devised Characters in Organisms Organism Devised Character Backbone Legs Hair Earthworm Absent Trout Present Lizard Human

Three Domains Domain is a larger, more inclusive category than a kingdom. Under this system, there are three domains— 1. Domain Bacteria 2. Domain Archaea 3. Domain Eukarya

The Tree of All Life

Classification Flip Book You Need: 3 pieces of construction paper Glue stick Marker for labels

Eubacteria Domain: Bacteria Cell type: prokaryotic Cell structure: Cell walls with peptidoglycan. Number of cells: Unicellular Mode or Nutrition: Autotroph or heterotroph Examples: Streptococcus, Escherichia coli

Archeabacteria Domain: Archaea Cell type: prokaryotic Cell structure: Cell walls without peptidoglycan. Number of cells: Unicellular Mode or Nutrition: Autotroph or heterotroph Examples: Methanogens, halophiles

Protista Domain: Eukarya Cell type: eukaryotic Cell structure: Cell walls of cellulose in some; some have chloroplasts. Number of cells: most unicellular; some colonial; some multicellular Mode or Nutrition: Autotroph or heterotroph Examples: Amoeba, Paramecium, slime molds, giant kelp

Fungi Domain: Eukarya Cell type: eukaryotic Cell structure: Cell walls of chitin Number of cells: most multicellular; some unicellular Mode or Nutrition: Heterotroph Examples: Mushrooms, yeasts

Plantae Domain: Eukarya Cell type: eukaryotic Cell structure: Cell walls of cellulose; chloroplasts. Number of cells: most multicellular: some green algae unicellular Mode or Nutrition: Autotroph Examples: Mosses, ferns, flowering plants

Animalia Domain: Eukarya Cell type: eukaryotic Cell structure: No cell walls or chloroplasts. Number of cells: multicellular Mode or Nutrition: Heterotroph Examples: Sponges, worms, insects, fishes, mammals