The Origin and Classification of Life
Classification and Evolution of Organisms
Taxonomy
• Taxonomy is the science of naming organisms and grouping them into categories.
• Derived from the Greek word taxis, which means arrangement.
Binomial System of Nomenclature
• The binomial system of nomenclature was developed by Carolus Linnaeus in 1758.
• The system uses only two latin names – the genus and the specific epithet for each species of organism.
Carolus Linnaeus
Binomial System of Nomenclature
• A species is a population of organisms capable of interbreeding and producing fertile offspring.
• A genus is a group of closely related organisms.
Hierarchy of Classification
Domains
• A Domain is the largest category of organisms.• There are three main domains: Eubacteria,
Archaea, and Eucarya.• The Eubacteria and Archaea are prokaryotic
and the Eucarya are eukaryotic.
Domains of Life
Kingdom
• A kingdom is a subdivision of a domain.• There are several kingdoms within the
Eubacteria and Archaea based primarily on differences in the metabolism and genetic composition of the organisms.
Kingdom
• There are four kingdoms within the Domain Eucarya.– Plantae– Animalia– Fungi– Protista (protozoa and algae)
Kingdoms
Phylum
• A phylum is a subdivision of a kingdom.• Organisms are based into phyla based upon
careful investigation of their structure, metabolism, and biochemistry.
Phylum
• An attempt is made to classify natural groups rather than imposing artificial subdivisions.
• Only flowering plants produce flowers and have seeds; conifers lack flowers but have seeds in cones; ferns lack flowers, cones, and seeds; and mosses lack tissues for transporting water.
Class
• A class is a subdivision within a phylum.• Within the phylum Chordata within the the
kingdom Animalia, there are seven classes: mammals, birds, reptiles, amphibians, and three classes of fish.
Order
• An Order is a category within a class.• The order Carnivora is an order of meat-eating
animals within the class Mammalia.
Family
• A Family is a subdivision of an order that consists of a group of closely related genera, which in turn are composed of closely related species.
Family
• The cat family, Felidae, is a subgroup of the order Carnivora; it includes many species in several genera, including the Canada lynx and bobcat (genus Lynx); the cougar; the leopard, tiger, jaguar, and lion (genus Panthera); the house cat (genus Felis); and several other genera.
All Life On Earth
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Sciurus
Species: Vulgaris
Classification of HumansTaxonomic Category
Human Classification
Characteristics Other Representatives
Domain Eucarya Cells containing a nucleus and other organelles
Plants, animal, fungi, protozoa, algae
Kingdom Animalia Eukaryotic heterotrophs, usually motile, specialized tissues
Sponges, jellyfish, worms, clams, insects, snakes, ctas
Phylum Chordata Stiffening rod down back
Fish, amphibians, reptiles, birds, mammals
Classification of HumansTaxonomic Category
Human Classification
Characteristics Other Representatives
Class Mammalia Hair and mammary glands
Kangaroos, mice, whales, skunks, monkeys
Order Primates Relatively large brain and opposable thumb
Monkeys, gorillas, chimpanzees, baboons
Family Hominidae Primates that lack a tail and have an upright posture
Humans and extinct relatives (australopithecus, Paranthropus, Homo)
Classification of HumansTaxonomic Category
Human Classification
Characteristics Other Representatives
Genus Homo Hominids with large brains
Humans are the only surviving member of the genus (past members: homo erectus, homo neanderthalensis)
Species Homo Sapiens Humans
Phylogeny
• Phylogeny is the science that explores the evolutionary relationships among organisms, seeking to reconstruct evolutionary history.
• Taxonomists and phylogenists work together, so that the products of their work are compatible.
Evidence Used to Establish Phylogenetic Relationships
• Several lines of evidence are used to develop evolutionary histories: fossils, comparative anatomy, life cycle information, and biochemical and molecular evidence.
Top Related