Classification of Organisms Categories of Biological Classification Taxonomy

Classification of Organisms

Categories of Biological Classification • Taxonomy This is the science of classifying and naming things. Susie b o B Jim Mar y Katie Phillip Fra nch eska Renea’ Becky Sam e s l e h C

• It is impossible for postal workers to sort all the mail by the first name of the addressee only.

• It is also impossible for biologists to memorize every name of the more than 30 million organisms on the Earth.

• To make sorting mail easier, postal workers sort first by zip code, then by street name and house number.

• In the same way, biologists group organisms into large categories, which are then placed into successively smaller and more specific groups. Animals Mammals Cats. Cat House

The Development of Classification Aristotle (Greek philosopher and biologist) was the first to classify organisms on the basis of their structural similarities. John Ray, English naturalist, introduced the new concept of species. (1627 – 1705) Carolus Linnaeus – (1707 -1778), a Swedish Botanist, collected and classified flowers, etc… He devised a scheme of arranging organisms into an ascending series of groups of ever increasing inclusiveness. Known as the hierarchical system of classification.

• One of the earliest attempts to make some order out of the countless plants and animals came from Aristotle. 384 -322 BC

• More than 2, 000 years ago, the Greek philosopher and naturalist, Aristotle, grouped plants and animals according to their structural similarities.

Classification of Plants: Herbs - Shrubs - Trees - soft stems Many woody stems One primary woody stem

Classification of Animals: Air dwellers Land dwellers Water dwellers

There were many obvious problems with this method: What do you do with a goose? Air? Land? Water?

In addition…. . Is an ostrich more closely related to man or a duck?

• Later Greeks and Romans grouped plants and animals into basic categories such as trees, dogs, and horses.

• Eventually, each unit of classification came to be called a “genus, ” the Latin word for “group. ”

A genus is a taxonomic category containing similar species.

• Starting in the Middle Ages, genera (plural for genus) were named in Latin.

• Until the mid-1700 s, biologists named a particular type of organism by adding descriptive phases to the name of the genus.

• These phrases sometimes consisted of 12 or more Latin words! • They were called “polynomials. ” (from poly, meaning “many” and nomen, meaning “name”)

• The polynomial for the honey bee: bee Apis pubescens, thorace subgriseo, abdomine fusco, pedibus posticis glabis, untrinque , margine cialiatus.

• As you can see, polynomials became very large and awkward. • As a result, polynomials were often changed (given “nick names”) by biologists, and organisms were seldom known to everyone by the same name.

Carolus Linnaeus, a Swedish physician, began standardizing classification in the mid-18 th century. Because of this, he is considered to be the father of classification today. 1707 -1778

• A simpler system for naming organisms was developed by the Swedish biologist, Carl Linnaeus • His system used a two-word name for each species. • The genus, followed by single descriptive word. • This system is called binomial nomenclature (“two name” NAMING)

Linnaeus suggested using visible, common characteristics to group related organisms.

He proposed a classification scheme composed of seven categories which become more and more specific. Kingdom Phylum Class Order Family Genus Species

Each major category into which organisms are grouped is called a taxon (taxa is plural).

A way to remember all of the 7 levels in order: • • Kangaroos Play Checkers On Fancy Green Stools Make up your own! 5 points extra on the next test! *Keep it G-rated!

Think of classification as a way to file all of the organisms on Earth!

Levels of Classification • Seven Levels for Animals – Kingdom – Phylum – Class – Order – Family – Genus – Species Largest Smallest

Characteristics General More specific Specific Kingdom – a few general characteristics; many different organisms Phylum Class Order Family Genus Species – several very specific characteristics Number of Organisms Many Fewer One

What is a biological species? • A group of individuals who are potentially or actually interbreeding, and that are reproductively isolated from other such groups. This is the OFFICIAL biologists definition!

How does Linnaeus’ system work? We’ll use the animal kingdom to answer that question.

All of these organisms *have eukaryotic cells *are heterotrophic *do not have a cell wall

All of these ANIMALS have 1. A dorsal nerve cord 2. A notochord 3. Embryonic gill slits and belong to the phylum CHORDATA

All these CHORDATES have 1. Constant body temperature 2. Hair 3. Give birth to live young 4. Feed their young milk and all belong to the class MAMMALIA

These MAMMALS 1. Have tearing teeth 2. Eat meat primarily meat and are placed in the order CARNIVORA

All Carnivores that are cats belong to the family FELINIDAE Cats have: 1. Sensory whiskers 2. Typical cat skeletons 3. Retractable claws

The lion and tiger belong to the genus Panthera. The domestic cat belongs to the genus Felis.

The African lion is species leo. The Asian tiger is species tigris. The house cat is species domestica.

Linnaeus’ system for naming species using binomial nomenclature: The first name is the genus (capitalized first letter) and species. Both are underlined OR italicized. Homo sapiens or Homo sapiens The genus is a noun and the species is usually an adjective. (Example: Turdus migratorius is the scientific name of the common robin. Turdus refers to “thrush” and migratorius refers to migratory habits. )

• The genus is a noun and the species is usually an adjective. • (Example: Turdus migratorius is the scientific name of the common robin. Turdus refers to “thrush, ” and migratorius refers to migratory habits. )

Using Binomial Nomenclature Genus • Always written first • Begins with capital letter • May include more than one species • Always italicized or underlined (never both) species • Always written after Genus • Begins with lower case letter • Includes only one kind of organism • Always italicized or underlined (never both) For example: Felis domesticus or Felis domesticus

Under the binomial nomenclature system of Linnaeus, scientific names include the genus and species: Common name Asian Tiger Genus Species Panthera tigris African lion Panthera leo Domestic cat Felis domestica

Dichotomous key Field guides often use dichotomous keys to identify organisms: • A dichotomous key consists of pairs of descriptive statements.

A partial example: • 1 a. If the seed has wings, go to question #2 in the key. • 1 b. If the seed does not have wings, go to question #3 in the key.

Human Classification Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Mammalia Order: Primate Family: Hominidae Genus: Homo Species: Sapiens

Introduction to the Kingdoms and Domains Chapter 19

Kingdoms • For years organisms were divided into FIVE Kingdoms: – – – Bacteria Protista Fungi Plantae Animalia

• However, further studies indicated there are 2 very important subtypes of bacteria They have different chemicals in their cell walls and different properties.

Kingdoms • Now there is a more accurate SIX kingdom system in place Formerly called Monera Archaebacteria Eubacteria Protista Fungi Plantae Animalia • Let’s take a look at each one individually!

Archeabacteria Kingdom Archaebacteria • Unicellular prokaryotes with a distinctive cell membrane • Some are autotrophic- produce food by chemosynthesis • Can produce flammable gases as waste • May be descendents of first organisms on earth • Live in harsh environments such as: – Very salty lakes – Sulfurous hot springs – Intestines of mammals

Kingdom Eubacteria • • • Eubacteria Unicellular prokaryotes Reproduce by binary fission Can adapt to environmental changes Greatest number of living things on Earth “Normal Bacteria” (good and bad) Disadvantage – Cause tooth decay – Cause food poisoning • Advantage – Turn milk into yogurt and cheese

Kingdom Protista • Eukaryotic, Eukaryotic mostly single-celled organisms • Some multicellular • Contains all eukaryotes which are not: animals, plants, or fungi (50, 000 species) • May contain chloroplasts and perform photosynthesis • May feed on other organisms Protista • Example: amoebas

Kingdom Fungi • Over 100, 000 species • Made up of heterotrophic unicellular and multicellular eukaryotic organisms • Most sexual cycles are unknown…have some form of genetic recombination • Examples: mushrooms, puffballs, rusts, molds, and mildews Fungi

Kingdom Plantae • Consists of multicellular plants • Most are autotrophic and use photosynthesis as their energy source • Few are parasites • More than 350, 000 identified • Examples: mosses, ferns, trees, and flowers Plants

Kingdom Animalia • • Heterotrophic Most have symmetrical bodies Mobile in their environment Reproduce sexually using meiosis to combine genes from parents • Example: cows, horses, dogs, cats, lions, humans

Phylogeny • Evolutionary history. (How this organism has evolved over the years. )

Convergent Evolution • When two species evolve similarities, even though they are not closely related, often because they live in similar habitats.

Even though they developed in different parts of the world, cactuses and spurges look very similar.

Structures evolved this way are called: • Analogous characters.

Taxonomic Characters and Phylogenetic Reconstruction A major goal of systematics (classification of organisms) is to reconstruct the evolutionary tree or phylogeny that relates to all the existing and extinct species. This is done by studying features (or characters) of organisms. Taxonomists use characters to study variations of species. (Comparative Anatomy)

Embryology can be used to determine evolutionary relatedness.

Cladistics • This is a method of analyzing evolutionary relatedness. • Biologists infer relatedness based on similar common characters (characteristics).

Ancestral Characters • A characteristic that evolved from a common ancestor of both groups. • Having a backbone is considered an ancestral trait to both birds and humans.

Derived Character • It evolved in an ancestor of one group, but not in the ancestor of the other group. • Having feathers is considered to be a derived trait in birds, since it evolved in ancestors of birds, but not in human ancestors.

A nested hierarchy of taxa is called a cladogram. The cladogram + information about ancestry and evolutionary change = a phylogenic tree. Cladogram

Sources of Phylogenetic Information Characters used to construct cladograms are found in comparative morphology, comparative cytology, and comparative biochemistry. Comparative morphology examines varying shapes and sizes of organism structures, structures including their developmental origins. Comparative Biochemistry uses sequences of amino acids in proteins and sequences of nucleotides in nucleic acid to identify variable characters for constructing a cladogram. Comparative Cytology uses variation in numbers, shapes, and sizes of chromosomes and their parts to obtain characters for constructing cladograms.

Evolutionary Systematics • In this kind of analysis, scientists place varying degrees of importance on characters and evolutionary relationships.

Phylogenetic Tree • Biologists display their evolutionary systematic analysis in a branching diagram called a phylogenetic tree. • It is similar to the cladogram.

Some things we use to classify: • • • Shape/ size Coloration Embryology DNA Proteins/ amino acid sequences Similar Structures

Animal Symmetry 1. Symmetry applies to the arrangement or correspondence of body parts with reference to some axis of the body. (humans are symmetrical) 2. Asymmetry applies to body plans that are irregular in shape. (amoebas are asymmetrical. )

Spherical symmetry means that any plane passing through the center divides the body into equivalent, or mirrored halves. Found mainly in protists. rare in animals. Best suited for rolling or floating.

Radial symmetry applies to forms that can be divided into similar halves by more than two planes passing through a main axis. (ex. Tubular, vase, bowl shapes found in sponges, hydra, jellyfish, etc…)

Sea stars are radially symmetrical:

Bilateral symmetry applies to animals that can be divided into right and left halves.

Order in Diversity: More than 1. 5 million species of animals have been described. Thousands more are identified each year. Biologists group animals according to their evolutionary relationships as revealed by similarities of structures.

Conclusion • There an estimated 10 -30 million organisms. • Carolus Linnaeus helped to develop a simple system for naming all kinds of organisms. • We still use many of the principles that he developed around 1753.

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