CLASSIFICATION Ch. 17

What is Taxonomy?

Taxonomy The science of classifying living things.

What are 2 reasons we classify?

To make things easier to find. To show how things are alike. To be able to accurately name organisms.

What are 2 problems associated with classification?

2 Problems There are many different life forms. People disagree on how to classify.

Early Classification Systems

Who was the first person to classify organisms?

ARISTOTLE Divided organisms into 2 groups: Plants and animals

Aristotle further divided plants into groups based on size. Herbs Shrubs Trees (short) (medium) (tall)

Aristotle divided animals into groups based on habitat. air land water

What scientist developed the classification system we use today?

Carolus Linnaeus Swedish botanist. Classified organisms based on their physical and structural similarities. Two kingdoms- plant and animal. 7 taxons or levels of organization. Developed binomial nomenclature

What are the classification groups (used today) in order from largest to smallest

Classification Hierarchy Domain—largest group (recently established) Kingdom Phylum (“Division” used for plants) Class Order Family Genus Species—smallest group (exceptions)

King Phillip Came Over For Good Spaghetti

The Linnaean classification system has limitations. Linnaeus taxonomy doesn’t account for molecular evidence. The technology didn’t exist during Linneaus’ time. Linnaean system based only on physical similarities.

Physical similarities are not always the result of close relationships. Genetic similarities more accurately show evolutionary relationships.

How are organisms given names?

Binomial Nomenclature Two-part naming system devised by Linnaeus (still used today)

What are the rules for naming organisms?

Rules for Naming Organisms 1st word is the genus and is always capitalized. 2nd word is the species and is never capitalized. Latin is always used. Name is always written in in italics.

Binomial Nomenclature

Why is it important to use scientific names?

Why use Scientific Names? Latin is a universal language. They seldom change/less confusion. Show relationship of a species.

MODERN TAXONOMY RULES Evolutionary relationship among organisms Chromosome structure/karyotype Reproductive potential Biochemical makeup Embryological development

Classification is always a work in progress. The tree of life shows our most current understanding. New discoveries can lead to changes in classification. Until 1866: only two kingdoms, Animalia and Plantae Animalia Protista Fungi Plantae 1866: all single-celled organisms moved to kingdom Protista Archea Bacteria 1938: prokaryotes moved to kingdom Monera 1959: fungi moved to own kingdom 1977: kingdom Monera split into kingdoms Bacteria and Archaea

3-DOMAIN SYSTEM (used today) Domain Archaea—ancient bacteria; live in extreme environments (Kingdom Archaea) Domain Bacteria—most common bacteria (Kingdom Bacteria) Domain Eukarya—eukaryotic organisms 4 kingdoms

E. coli

What are the 4 kingdoms in the Domain Eukarya?

Kingdoms in Domain Eukarya Kingdom Protista Kingdom Fungi Kingdom Plantae Kingdom Animalia

Dichotomous Key A tool used to identify organisms Characteristics given in pairs Read both characteristics and either go to another set of characteristics OR identify the organism

Example of Dichotomous Key 1a Tentacles present – Go to 2 1b Tentacles absent – Go to 3 2a Less than 8 tentacles – Hydra 2b More than 8 tentacles–Go to 3 3a Tentacles hang down – go to 4 3b Tentacles upright–Sea Anemone 4a Balloon-shaped body–Jellyfish 4b Body NOT balloon-shaped - 5

KEY CONCEPT Modern classification is based on evolutionary relationships. Pangolin

Cladistics is classification based on common ancestry. Phylogeny is the evolutionary history for a group of species. evidence from living species, fossil record, and molecular data shown with branching tree diagrams

Cladistics is a common method to make evolutionary trees. classification based on common ancestry species placed in order that they descended from common ancestor Armadillo Glyptodon

A cladogram is an evolutionary tree that proposes how species may be related to each other through common ancestors. A clade is a group of species that shares a common ancestor. Each species in a clade shares some traits with the ancestor. Each species in a clade has traits that have changed.

Derived characters are traits shared in different degrees by clade members. FOUR LIMBS WITH DIGITS Tetrapoda clade 1 Amniota clade 2 Reptilia clade 3 Diapsida clade 4 Archosauria clade 5 EMBRYO PROTECTED BY AMNIOTIC FLUID OPENING IN THE SIDE OF THE SKULL SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW FEATHERS & TOOTHLESS BEAKS. SKULL OPENINGS BEHIND THE EYE DERIVED CHARACTER basis of arranging species in cladogram more closely related species share more derived characters represented on cladogram as hash marks

Nodes represent the most recent common ancestor of a clade. FOUR LIMBS WITH DIGITS Nodes represent the most recent common ancestor of a clade. CLADE Tetrapoda clade 1 Amniota clade 2 Reptilia clade 3 Diapsida clade 4 Archosauria clade 5 FEATHERS AND TOOTHLESS BEAKS. Clades can be identified by snipping a branch under a node. SKULL OPENINGS IN FRONT OF THE EYE AND IN THE JAW OPENING IN THE SIDE OF THE SKULL SKULL OPENINGS BEHIND THE EYE EMBRYO PROTECTED BY AMNIOTIC FLUID NODE DERIVED CHARACTER

Molecular evidence reveals species’ relatedness. Molecular data may confirm classification based on physical similarities. Molecular data may lead scientists to propose a new classification. DNA is usually given the last word by scientists!!!

Clades: Motorcycle Car Walking Bicycle airplane Derived Characters: Wings Wheels Passengers enclosed Clades: Motorcycle Car Walking Bicycle airplane