Organizing Life’s Diversity

Unit 5Chapter 17

What is classification?

the grouping of objects or information based on similarities

This helps biologists understand how organisms are related to each other.

This is useful in agriculture, forestry, biochemistry, and medicine (to name a few fields).

Taxonomists study taxonomy.

the branch of biology that groups and names organisms based on studies of their different characteristics

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Aristotelian classification

Life

Plant Animal

Herb Shrub Tree Aristotle grouped organisms based on appearance and abilities.

Carolus Linnaeus: 1707-1778

Swedish botanist Created modern

classification system based on physical and structural similarities

Modern taxonomists have altered the Linnaean system to reflect evolutionary relationships.

Binomial nomenclature

two-word naming system to identify organism Genus: group of related species

always capitalized Specific epithetic: particular characteristic

always lower case

Ex: Homo sapiens

Genus specific epithet

When writing the scientific name which is Latin, one must italicize when typing or underline when handwriting.

Common names Many people refer to

organisms by common names rather than scientific names.

Be careful that common names do not always reflect the biology of the organism.

Scientific name: Fragaria ananassa

Common name: strawberry

Dichotomous key: system to identify organisms and their scientific names A key is made up of sets of numbered

statements. Each set deals with a single characteristic of

an organism, such as leaf shape or arrangement.

How living things are classified

Taxon: a group of organisms (taxa, pl.)

These groups (taxa) can be very broad or very specific.

The taxonomic levels from most broad to most specific: kingdom, phylum, class, order, family, genus, species

Domain

Kingdom

Phylum

Class

Order

Family

Genus

Species

Eukarya

Animalia

Chordata

Mammalia

Carnivora

Felidae

Lynx

Lynx rufus

Lynx canadensis

Bobcat Lynx

Taxonomic levels

Comparing related animals

Lynx rufus, lynx Panthera concolor, mountain

lion Lynx canadensis, bobcat

Which two are more related? How do you know?

Mountain lion

BobcatLynx

What determines evolutionary relationship? Anatomy and physiology

Common structures imply a common ancestor. Breeding and behavior patterns Geographic distribution DNA and biochemistry

DNA comparisons between these plants show almost no difference.

Phylogeny: Studying the evolutionary histories and relationships of organisms

Cladistics: a phylogenic study that assumes probabl groups of organisms diverged and evolved

Theropods

Allosaurus

Sinornis

Velociraptor

Archaeopteryx

Light bones3-toed foot;

wishboneDown

feathers

Feathers withshaft, veins,and barbs

Flight feathers;arms as long

as legs

Fan model to indicate phylogeny

Modern six-kingdom classification

Archaebacteria: prokaryotic Eubacteria: prokaryotic Protists: eukaryotic Fungi: eukaryotic Plants: eukaryotic Animals: eukaryotic

Archaebacteria overview Most live in extreme

environments such as swamps, deep-ocean hydrothermal vents, and seawater evaporating ponds.

Most do not use oxygen to respire.

Eubacteria overview

very strong cell walls

a less complex genetic makeup than found in archaebacteria or eukaryotes

diverse habitat

Protists: A diverse group

• Kingdom Protista contains diverse species that share some characteristics.

• A protist is a eukaryote that.

Cilia

Oral groove

Gullet

Micronucleus and macronucleus

Contractile vacuole

Anal pore

A Paramecium

Protist overview lacks complex organ

systems lives in moist environments diverse metabolism

Fungi overview Decomposes matter by

absorbing materials Multicellular or

unicellular

Plant overview

Multicellular Photosynthetic:

produce oxygen Immobile Cell walls

Animal overview

Multicellular Mostly mobile Lack cell walls Diverse habitats