History of Classification Finding Order in Diversity

History of Classification For more than 3.5 billion years, life on Earth has been constantly changing. Natural Selection has led to a staggering diversity of organisms. Biologists have identified and named about 1.5 million species so far Estimate that 2 and 100 million have not yet been discovered.

Classification Why classify? By using a scientific name, biologists can be certain that everyone is discussing the same animal. Taxonomy A discipline of classifying organisms and assigning each organism a universally accepted name.

History of Classification How are living things organized for study? a. When you hear the word “bird”, what mental picture appears? A flying animal that has feathers

History of Classification In a good system of classification, organisms placed into a particular group are more similar to each other than they are to other organisms in different group. EX: We use a classification system. When you refer to “teachers”, or more specifically “zoology teachers”.

History of Classification By the 18th century, European scientists realized that referring to organisms by common names was confusing. Common names vary among languages. For example a cougar can also be called a puma, a panther or a mountain lion. Southern california are called mountain lions. Florida calls them panthers.

History of Classification In England, the word buzzard refers to a hawk whereas in many parts of the US, buzzard refers to a vulture.

History of Classification Aristotle’s System The first attempt at standardizing scientific names basically described the physical characteristics of a species. EX: scientific name of a particular tree might be “Oak with deeply divided leaves that have no hairs on their undersides and no teeth around their edges.”

History of Classification Carolus Linnaeus Swedish botanist who lived during the 18th century. binomial nomenclature Classification system in which each species is assigned a two-part scientific name. Bi is latin for “two” and nomen is latin for “name”.

1. Linnaeus’s System of Classification Classification system with 7 levels Each level called taxon (plural: taxa) Why 7 levels? Lots of organisms

Classification System Kingdom Phylum Class Order Family Genus Species Country State County City Neighborhood Street House #

Kingdom Largest taxonomic group, consisting of closely related phyla Eukaryotes 2 original kingdoms Animalia Plantae

Phylum Group of closely related organisms that share important characteristics Ex: Chordata – Humans & Bears

Class & Order Class – group of similar orders Mammalia Internal regulation of body temp. (warm-blooded) Have body hair Produce milk for young Order – broad taxonomic category composed of similar families Carnivora Bears - Ursidae Dogs – Canidae Cats - felidae

Family Share many characteristics EX: Bears – Ursidae and Ailuropoda Polar bears Grizzly bears Panda bear Grouped in larger category, Ursidae (all bears)

Genus & Species Genus Group of closely related species, and the first part of the scientific name in binomial nomenclature. Species Group of organisms that can breed and produce offspring that are fertile. Grizzly Bear Ursus arctos Giant Panda Ailuropoda melanoleuca Polar Bear Ursus maritimus

Binomial Nomenclature 2-word naming system Each species is assigned a 2 part name Always written in italics or underlined First word is always capitalized Genus species Two smallest categories, genus and species (one organism). Ursus are grouped in a larger category. EX: polar bear in this genus Grizzly bear ~ Ursus arctos

Questions??? How are organisms classified? Living things are classified according to shared characteristics and organized into 7 categories. What is binomial nomenclature? A two-word naming system Explain the difference between Aristotle’s system and Linnaeus's system of classification? Aristotle’s common name system which can differ due to in languages. Linnaeus’s system of binomial nomenclature

Modern Evolutionary Classification What characteristics do scientists use to classify organisms?

Modern Classification Organisms choose with whom they will mate. Group organisms according to biologically important characteristics. Linnaeus’s system grouped animals according to visible similarities and differences. Problems???

Modern Classification How would you classify the crab, limpet, and barnacle?

Look more closely! Limpet and barnacle larvae are very different. CRAB Limpet and barnacle larvae are very different. Barnacles have jointed limbs. Limpets DON’T ! Barnacles have a segmented body Barnacles have an exoskeleton that molts.

Look more closely! Crab and barnacle larvae are very similar LIMPET CRAB BARNACLE Crab and barnacle larvae are very similar Barnacles have jointed limbs. So do CRABS ! Barnacles have a segmented body Barnacles have an exoskeleton that molts. Barnacles and crabs share an evolutionary ancestor that is more recent than the ancestor that barnacles share with limpets.

Modern Classification Limpet’s are mollusks and have a foot like clams and limpet’s shell is one structure whereas barnacles’ shell have interlocking plates.

Modern Classification Evolutionary Classification Darwin’s ideas about descent with modification gave rise to the study of phylogeny. The study of evolutionary relationships among organisms. Evolutionary relationship of the Phylum Chordata

Modern Classification Evolutionary classification Method of grouping organisms together according to their evolutionary history. All members of a genus share a recent common ancestor.

Modern Classification Cladogram Diagram that shows the evolutionary relationships among a group of organisms. Derived character Characteristic that appears in recent parts of a lineage, but not in its older members. Derived Characters

Modern Classification Similarities in DNA and RNA Genes of many organisms show important similarities. DNA can be used to determine classification and evolutionary relationships. They urinate on their legs which cools and removes body heat and storkes behavior the same way. Are these organisms related?

Traditionally these first two were Similarities in DNA can be used to help show evolutionary relationships and how species have changed. African vulture American vulture Stork Traditionally these first two were classified together in falcon family. Storks were put in a separate family.

The only other bird that does this is the STORK. American vultures have a peculiar behavior. When they get overheated, they urinate on their legs to cool off African vulture American vulture Stork The only other bird that does this is the STORK.

DNA comparisons showed more similarities between American vulture and stork DNA than DNA from the two kinds of vultures suggesting a more recent common ancestor between storks and American vultures. African vulture American vulture Stork

Questions??? What characteristics do scientists use to classify organisms. Biological: Structure (including similarities in DNA) Physiological behavioral Evolutionary relationships; phylogeny How are evolutionary relationships important in classification? Accurate placement of organisms within their phylogenic tree.

What are the three-domain systems of classification? Domains and Kingdoms What are the three-domain systems of classification? Bacteria Archae Eukaryota

3 Domain System Modern organisms have been grouped according to how evolved Domain More inclusive category; larger than a kingdom. 3 Domains: Bacteria – unicellular & prokaryotic Archaea - extremophiles Eukarya – unicellular & multicellular Eukaryotes

3 Domain System Eubacteria Domain of unicellular prokaryotes that have cell walls containing peptidoglycans

3 Domain System Archaea Domain of unicellular prokaryotes that have cell walls that do not contain peptidoglycan They live in extreme environments. Colonies of haloarchaea on agar plates

3 Domain System Eukarya Domain of all organisms whose cells have nuclei, including protists, plants, fungi and animals.

Tree of Life

6 Kingdoms of Life The six-kingdom system of classification includes: Eubacteria Archaebacteria Protista Fungi Plantae Animalia

Domain Eukarya

Kingdom Protista The kingdom Protista is composed of eukaryotic organisms that cannot be classified as animals, plants or fungi, They can be unicellular or multicellular; photosynthetic or heterotrophic; and can share characteristics with plants, fungi or animals.

Kingdom Fungi Kingdom composed of heterotrophs; many obtain energy and nutrients from dead organic matter (decomposers). They can be either multicellular (mushrooms) or unicellular (yeasts).

Kingdom Plantae Members of the Kingdom Plantae are multicellular, photosynthetic autotrophs that have cell walls containing cellulose. Plants are nonmotile – they cannot move from place to place.

Kingdom Animalia Members of the Kingdom Animalia are multicellular eukaryotic heterotrophs whose cells do not have cell walls. There is great diversity within the animal kingdom, and many species exist in nearly every part of the world.

Questions??? What are the three-domain systems of classification? Bacteria, Archae and Eukarya What are the six kingdoms of life? Eubacteria, Archaebacteria, Protista, Fungi, Plantae, Animalia