UNIT IV DIVERSITY OF LIVING THINGS Scientific Classification

Why Do We Classify Organisms? CLASSIFICATION the grouping of organisms by similarities Biological classifications are based on how organisms are related. Group A Group B Why Do We Classify Organisms? Biologists group organisms to represent similarities and proposed relationships. Classification systems change with expanding knowledge about new and well-known organisms.

Classification Binomial Nomenclature Hierarchical Classification Two part name (Genus, species) Hierarchical Classification Seven Taxonomic Catagroies Systematics Study of the evolution of biological diversity Taxonomy: the branch of biology concerned with the grouping and naming of organisms; the study of classification

Taxonomy Organisms are classified into a hierarchy of groups and subgroups based on similarities that reflect their relationships over a period of time.

Cladogram or Phylogenic Tree A branching, treelike diagram in which the endpoints of the branches represent specific species of organisms. It is used to illustrate phylogenetic relationships and show points at which various species have diverged from common ancestral forms. Animation - Phylogenetic Trees

Taxonomic Diagrams Phylogenetic Tree Cladogram Taxonomic Diagrams Mammals Turtles Lizards and Snakes Crocodiles Birds Mammals Turtles Lizards and Snakes Crocodiles Birds Phylogenetic Tree Cladogram Taxonomic Diagrams Sometimes, biologists group organisms into categories that represent common ancestries, not just physical similarities. Early naturalists used physical characteristics and later, fossil data, attempting to represent evolutionary relationships among organisms. Today, modern classification systems use fossil data, physical characteristics and DNA/RNA information to draw increasingly more accurate branching diagrams. Phylogenetic trees, or phylogenies, represent hypothesized evolutionary relationships among organisms and may include extinct as well as modern species. Cladograms are based only on characteristics observable in existing species. The branching patterns in a cladogram are defined by the presence of unique, evolving innovations (derived characteristics) shared by all members of the group. References Campbell, N. E. & Reece, J. B. (2002). Biology (6th ed.). Benjamin Cummings. Judd, W. S., Campbell, C. S., Kellogg, E. S., Stevens, P. F., & Monoghue, M. J. (2002). Plant Systematics: A Phylogenetic Approach, (2nd ed.). Sinauer Associates, Inc. Image References Dykinga J. Buffalo. USDA Agricultural Research Service. http://www.ars.usda.gov/is/graphics/photos/ Bauer, S. Turkey. USDA Agricultural Research Service. http://www.ars.usda.gov/is/graphics/photos/ Alligator, unknown NOVA Development Corp. (1995) Insects & Reptiles #0517. Art Explosion, Volume 2 Clip Art NOVA Development Corp. (1995) Insects & Reptiles #0557. Art Explosion, Volume 2 Clip Art

Tree of life Biology: Samples -           

Aristotle’s Groups HISTORY: Aristotle- developed the 1st method of classification He divided all living things into 2 major groups Aristotle’s Groups He divided all living things into 2 major groups 1. Plants classified by size and structure 2. Animals classified by habitat (where they lived)

HISTORY: Aristotle Problems with his system: Frogs live in both water and on land Bats, birds and flying insects were grouped together

Kingdom Phylum Class Order Family Genus Kingdom – largest group Phylum (sing.) Phyla (pl.)(Plants don’t have phyla, they have divisions.) Class Order Family Genus Species Phylum Class Order Family Genus These two taxa make up the scientific name. Species

K__________ p__________ c_________ o___________ f________ g_________ s________. King Phillip came over for great soup.

HISTORY: Carolus Linnaeus- developed the modern system of classification Father of Taxonomy

Binomial Nomenclature Carolus von Linnaeus Two-word naming system Genus Noun, Capitalized, Underlined or Italicized Species Descriptive, Lower Case, Underlined or Italicized

Binomial Nomenclature Binomial nomenclature is a standard way of identifying a species with a scientific two-word name. The first word is the genus name and the second the species name. Scientific name - 2 Latin names - Genus and species - Capitalize the first letter of the genus - Do NOT capitalize the species - ALWAYS underline or use italics Ex. Homo sapiens

Binomial Nomenclature Scientific Name: Homo sapiens Common Name: Albert Einstein

Binomial Nomenclature Scientific Name: Rudbeckia hirta Common Name: Gloriosa daisy or Black-eyed Susan

Binomial Nomenclature Scientific Name: Pinus virginianis Common Name: Virginia Pine

Binomial Nomenclature Scientific Name: Harmonia axyridis Common Name: Asian Ladybug

Binomial Nomenclature Scientific Name: Ophiophagus hannah Common Name: King Cobra

MODERN CLASSIFICATION SYSTEM Organisms are grouped together on the basis of: Similarity in structure Felis domesticus Panthera leo Felis rufus

Similarity in structure Canis lupus

Similarity in structure Canis latrans

Similarity in structure Canis domesticus

Organisms are grouped together on the basis of: Similarity in genetic makeup (biochemistry) Similarities among organisms on the structural and metabolic levels are reflected in the large degree of similarity in proteins and nucleic acids of different organisms. Diversity is the product of variations in these molecules.

Organisms are grouped together on the basis of: Similarity of embryonic development

Evolution: Library: Common Past, Different Paths

Organisms are grouped together on the basis of: Similarity in evolutionary history Phylogeny: the evolutionary history of a species based on comparing relationships between species using the fossil record

Organisms are grouped together on the basis of: Similarity in behavior

Systematics: Evolutionary Classification of Organisms Systematics is the study of the evolution of biological diversity, and combines data from the following areas. Fossil record Comparative homologies Cladistics Comparative sequencing of DNA/RNA among organisms Molecular clocks

Classification is based on close evolutionary relationships of organisms. Organisms classified in the same taxa (pl.) (taxon, sing.) share a common ancestry. They have evolved from the same common ancestral organism.

Evolutionary Relationships Classification is hierarchal each successive level is smaller and more closely related than the one before it

Species organisms that belong to the same species can mate AND produce FERTILE offspring.

+ = Horses and donkeys can mate. They produce a mule. Mules are INFERTILE + =

+ = Lions and tigers can mate. They produce a liger. Ligers are INFERTILE + =

Why use scientific names? Common names do not indicate how organisms are related or classified. Common names can be misleading. (e.g., seahorse, weeping willow) Organisms with more than one common name leads to mass confusion.

Why Latin? Latin is no longer spoken, and therefore, does not change as spoken languages do. So, scientific names remain the same forever.