Classification
of Organisms
Classification of Organisms
► The
study of the kinds and diversity of
organisms and their evolutionary
relationships is called taxonomy
 Taxonomy is the work involved in the original
description of a species.
Linnaeus
► Carolus
Linnaeus (1707–1778),
a Swedish physician and
botanist
► Sought to classify life′s
diversity “for the greater glory
of God.”
► Binomial Nomenclature:
two-part Latin name of a
species
► any grouping of animals that
shares a particular set of
characteristics forms an
assemblage called a taxon
Modern taxonomists use 7 taxa:
►kingdom,
phylum, class,
order, family, genus and
species
as taxa increase organisms
get more specific
Binomial Nomenclature:
►When
a species is talked about
only the genus and species names
are used
 this is called the scientific name
 unique to each type of organism
Writing Scientific Names
► the
genus names is always capitalized
► both names are either italicized or
underlined
 leave a space in the underline between names
ex.
Homo sapien
Felis leo
Kingdoms of Life
►In
1969, Robert H. Whitaker
classified kingdoms based on
cellular organization and mode of
nutrition
 this lead to the formation of the 5
kingdoms
5 Kingdoms of Classification:
Monera: comprised of bacteria and cyanobacteria
► distinguished by being single cell prokaryotes
Protista: comprised of Amoeba, Paramecium
etc….
► distinguished by being single celled eukaryotes
Plantae: multi-cellular photosynthetic
eukaryotes
► plants have cell walls and are non-motile
5 Kingdoms of Classification:
Fungi: multi-cellular heterotrophic eukaryotes
► fungi have cell walls and usually non-motile
► digest organic matter extra-cellularly (outside of
cell) and absorb the breakdown products
Animalia: multi-cellular heterotrophic eukaryotes
► animal cells lack a cell wall and usually motile
► feed by ingesting other organisms or parts of
other organisms
DOMAINS???
►Many
taxonomists have pushed the
idea that the five kingdom system
isn’t enough
 they feel that organisms share too
much similarities and need to be
grouped otherwise
the push has led to the addition of
3 domains
►
3 Domains
1.
Archae: bacteria that live in extreme
conditions
2.
Eubacteria: “true bacteria”
3.
Eukarya: all eukaryotic organisms
Modern Taxonomic System
Dichotomous Key
►Scientist
use
dichotomous key in order
to correctly identify living
and non-living things.
Dichotomous Key
Keys consist of a series of choices
that lead the user to the correct
name of a given item.
"Dichotomous" means "divided into
two parts".
Therefore, dichotomous keys always
give two choices in each step.
Dichotomous Key
Linking Classification and Phylogeny
►
Systematists use branching diagrams called phylogenetic
trees to depict their hypotheses about evolutionary
relationships.
Linking Classification and Phylogeny
► Ancestral
Characteristics – a characteristic
that evolved from a common ancestor
 Backbone that is present in birds and alligators
► Derived
Characteristic - characteristic that
evolves in one group but not another.
 Feathers in birds but not in other mammals
Clades and Cladograms
► Cladogram
- A diagram depicting patterns of
shared characteristics among species.
Valid Clades
Monophyletic- Pertaining to a grouping of species consisting of an ancestral species
and all its descendants; a clade
Paraphyletic- Pertaining to a grouping of species that consists of an ancestral species
and some, but not all, of its descendants.
Polyphyletic- Pertaining to a grouping of species derived from two or more different
ancestral forms.