What Is Classification

What is classification?

• the grouping of objects or information based on similarities

What is taxonomy?

• the branch of biology that groups or names organisms based on the study of their different characteristics

Aristotle’s System of Classification

• Greek Philosopher (384 -322 BC)

• Grouped plants and animals

– Plants: Herbs, Shrubs and Trees

– Animals: on land, in the air, or in water

• Based on structural characteristics

• Example: classified birds, bats and flying insects together

Linnaeus’ System of Classification

• Lived:1707-1778

• GOAL: To classify all known organisms

• Used flower parts to assign different categories (species, genus, order, class)

• Based on morphology (physical and structural similarities)

• Biologists realized that bats and birds can both fly, but bats have hair and produce milk for their young and now classified as mammals

Binomial Nomenclature

• Bi- means 2

• Nom- means name

• In Latin or Greek

• Genus species

• Genus means plural or genera and consists of a group of similar species

• Species describes a characteristic of the organism

• Genus is capitalized and species is lowercase

• If written (underline) or if typed (italics)

Example: European Honeybee: Apis mellifera

Scientific Name

• Genus species is the combination of genus and species

• Species alone is just the description of a characteristic

• Characteristics include: size, color (of body, feet, wings)

Examples of current scientific names

• Red Oak: Quercus rubra

• Willow Oak: Quercus phellos

Biological Classification based on:

• Relationships between organisms

• Fossil record interpretation

• Similarities in structural and chemical makeup

• External and Internal structures

• Geographical distribution

• Chemical makeup

Why Latin?

• Common names (honeybee) varies from country to country due to language differences

• Universal language between scholars

• Most scholars were scientists

• Scientific names are universal

The Six Kingdoms

Types of characteristics used in classification:

• Morphology

• Embryology

• Chromosomes

• Biochemistry

• Physiology

• Phylogeny

• Biosystematics

Morphology

• Structure and anatomy; Reflects evolutionary relationships

• Example: Wings of a bird and wings of an insect arise from different tissue within the embryo; Bones of the forelimb in a lizard are similar to those in the forelimb of the cat

Homologous Structures

Vestigial Structures

Embryology

• Development of plants and animal cells still inside seed or egg

Chromosomes

• Structure enclosed in the DNA of a cell, which carries genetic information; Chromosome number and shape (circular or linear)

Biochemistry

• Chemical make-up of the body and its systems; Metabolism; Sequence of nucleotide bases (DNA); Comparing: Proteins, amino acids sequences, DNA and RNA

Physiology

• Biological function of how the organism works; Bacteria: Fermentation of sugar (lactose), Uses citric acid as their sole source of carbon; Organisms may look similar, but different based on physiology

Phylogeny

• Evolutionary history; Line of evolutionary descent; How organisms have evolved; Characteristics based upon the same characteristics (by ancestry); GOAL: to produce classification system that is easy to use and informative regarding patterns of evolution.

Biosystematics

• Reproductive compatibility and gene flow; Classification hierarchy; Determined by similar characteristics; Characteristics: structural, chromosomal, or molecular feature distinguishing one group from another

Know the classification hierarchy:

• Kingdom-Phylum-Class-Order-Family-Genus-Species

• Least Similar……to……Most Similar

Classification Hierarchy – using humans as an example:

Kingdom - Animalia

• Eukaryotic (has cell nucleus); motile; multi-cellular; no cell walls or chlorophyll; internal cavity for digestion of nutrients

Phylum - Chordata

• Dorsal hollow nerve cord, notochord, and pharyngeal pouches

Class - Mammalia

• Warm-blooded; mammary glands; more or less covered with hair; well-developed brain

Order - Primate

• Good brain development; opposable thumb; sometimes big toes; lacking claws, scales, horns and hooves

Family - Hominidae

• Limb anatomy suitable for upright stance and bipedal locomotion

Genus - Homo

• Maximum brain development (particular portions); Hand anatomy suitable for making tools

Species - Homo sapien

• Body proportion of modern humans; speech centers of brain well-developed; sapiens means “wise”

Six Kingdoms

Archaebacteria

Eubacteria

Protista

Fungi

Plantae

Animalia