Taxonomy “The Study of Classification”

What do you think? What does classification mean? Why is classification important? When do we use classification systems in our everyday lives? Books at the library, iPods and movies, even people!

Objectives Learn about the history of classification systems Recognize Linnaeus’ contribution Discuss classification keys and their usefulness Study Phylogenic trees and Cladograms Outline the 6 Kingdom system

What exactly is classification? Classification is a branch of Biology called Taxonomy. Taxonomy classifies based on similarities …but it wasn’t always this way!

Meet Aristotle (350 BC) Aristotle classified all living organisms as either a plant or an animal. He further classified animals by where they lived, and plants by their size.

Aristotle’s Classification Scheme ALL LIVING ORGANISMS PLANTS ANIMALS

PLANTS SHORT (Herbs) MEDIUM (Shrubs) TALL (Trees)

ANIMALS LAND WATER AIR

What are some problems with this classification system? Some animals live in more than one habitat during their lives. Most plants start small and grow larger.

These problems were recognized by Carolus Linnaeus “The Father of Modern Taxonomy”

Carolus Linnaeus Linnaeus was a Swedish botanist who lived in the 18th century. He decided to classify organisms based on their visible similarities and differences in structure.

Carolus Linnaeus Linnaeus made three huge contributions to modern taxonomy: Using structural criteria for classification Establishing the 7 taxa currently used. Created the Binomial Nomenclature

The 7 Taxa Kingdom Phylum Class Order Family Genus Species Pneumonic Device: King Phillip Came Over For Ginger Snaps Kingdom Phylum Class Order Family Genus Species Used in Scientific Names

7 Taxa Kingdom Phylum Class Order Family Genus Species

Did you notice? As you go down through the 7 taxa, you get more and more details about the organism you are looking at. Organisms get more and more similar from top to bottom.

Let’s Classify Us! Let’s classify a human: Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Primates Family: Hominidae Genus: Homo Species: Sapiens

Binomial Nomenclature Binomial nomenclature is a “two word” naming system. The first term describes the organisms genus while the second term describes the species.

Genus and Species Organisms placed in the same genus have similar structures (look the same). Organisms with the same species name are so similar they would be able to reproduce under normal circumstances to produce fertile offspring.

Binomial Nomenclature Scientific names are written in Latin and have something to do with the organisms characteristics or where they live. (Castor canadensis) (Ursus horribilus) Scientific names are written in italics or underlined. The first term is always capitalized while the second isn’t Example: Homo sapiens  humans Homo sapiens H. sapiens

Examples of Scientific Names Canis lupus  Wolf Canis familiaris  Dog These organisms are structurally similar (same genus) but different species (cannot reproduce under normal circumstances to produce fertile offspring)

Scientific Names Equus caballus - horse Equus asinus – donkey When a donkey and a horse reproduce, their offspring is a mule, which is sterile. (1 in 100 000 will have an offspring)

Check out the Scientific Names

KEY TERMS SYSTEMATICS Scientific study of the diversity of organisms and their natural (evolutionary) relationships A systematist seeks to reconstruct phylogeny

KEY TERMS PHYLOGENY MONOPHYLETIC Evolutionary history of a species or other taxonomic group MONOPHYLETIC Said of a group consisting of organisms that evolved from a common ancestor

KEY TERMS CLADISTICS Classification of organisms based on recency of common ancestry rather than degree of structural similarity

Cladistics Cladists emphasize phylogeny by focusing on when evolutionary lineages (lines of descent) divide into two branches Cladists develop cladograms

KEY TERMS CLADOGRAM A diagram that illustrates evolutionary relationships based on the principles of cladistics

Building a Cladogram

Characters TAXON VASCULAR TISSUES SEEDS FLOWERS Moss A A A Fern P A A Pine P P A Figure 18.7: Building a cladogram. Refer to the table as you follow the process in (a) through (c). (Adapted from Dr. John Beneski, Department of Biology, West Chester University, West Chester, Pennsylvania) Daisy P P P

(a) All of the plant groups shown here except mosses have vascular Pine Moss Daisy Fern Common ancestor with vascular tissues Figure 18.7: Building a cladogram. Refer to the table as you follow the process in (a) through (c). (Adapted from Dr. John Beneski, Department of Biology, West Chester University, West Chester, Pennsylvania) Node 1 Common plant ancestor (a) All of the plant groups shown here except mosses have vascular

(b) Seeds are a shared character for all plant groups Pine Moss Daisy Fern Node 2 Common ancestor with vascular tissues Figure 18.7: Building a cladogram. Refer to the table as you follow the process in (a) through (c). (Adapted from Dr. John Beneski, Department of Biology, West Chester University, West Chester, Pennsylvania) Node 1 Common plant ancestor (b) Seeds are a shared character for all plant groups shown here except mosses and ferns.

(c) Of the plant groups shown here, only the daisy produces flowers. Pine Moss Daisy Fern Node 3 Common seed- producing ancestor Node 2 Common ancestor with vascular tissues Figure 18.7: Building a cladogram. Refer to the table as you follow the process in (a) through (c). (Adapted from Dr. John Beneski, Department of Biology, West Chester University, West Chester, Pennsylvania) Node 1 Common plant ancestor (c) Of the plant groups shown here, only the daisy produces flowers.