Biology Chapter 17
Organizing Life’s Diversity
17.1 Aristotle

Aristotle developed the first system
of biological classification
• He divided all organisms into plants or
animals
He divided plants into shrubs, herbs, and
trees
 He divided animals into groups based on
characteristics such as habitat and physical
features

17.1 Linnaeus

Linnaeus developed a classification system
in the late 1700’s that grouped organisms
based on structural similarities
• We still use this system as the basis for
modern classification
• Linnaeus developed the idea of binomial
nomenclature-each organism is identified by 2
names, the genus and the specific epithet
• This system also indicates the evolutionary
relationships between organisms
17.1 Scientific Names

Latin is used for scientific naming of
organisms
• This language is used because it does
not change as a result of the fact that it
is a “dead” language
Scientific names are to be written in italics
when typed and underlined when
handwritten
 The first letter of the genus is uppercase
and the first letter of the specific epithet is
lowercase

17.1 Uses of Taxonomy
Taxonomy is used to study
relationships between living and
extinct species
 Taxonomy is used to easily identify
unknown or unfamiliar organisms
 Taxonomy can also be used to
predict whether or not new species
have economic value based on
similar species

17.1 Taxonomy of Living Things


Organisms are classified first by broad
characteristics, then are further divided by
more and more specific characteristics
until individual species are identified
In order from least specific to most
specific , organisms are classified in the
following pattern:
domain, kingdom, phylum, class, order,
family, genus, species

domain is a recent addition to taxonomy and may not
yet be widely used or accepted
17.2 Evolutionary Relationships

Evolutionary Relationships are determined
based on similarities in five
characteristics:
• Structure-physical characteristics
• Breeding behavior- methods to attract a matesounds, dances, etc.
• Geographical distribution-where in the world
they live, including climate and physical
location
• Chromosomes- numbers and structures of
chromosomes
• Biochemistry- DNA sequences and protein
chains
17.2 Phylogeny

Phylogeny is the evolutionary history
of a species
• Phylogenic classification is a way of
classifying organisms that shows the
evolutionary relationships between them
• Two types of phylogenic diagrams:
Cladogram
 Fan model

17.2 Cladistics

Cladistics assumes that as organisms
evolve from a common ancestor, they
maintain some derived traits
• Cladistics uses cladograms, or branching
diagrams that show relationships among
organisms





Each branch shows a different organism
The closer together 2 branches are, the closer the
relationship between the organisms
Changes in traits may be written under the branches
They do not show direct ancestry, only likely
evolutionary patterns
An example is on p. 452
Cladistics
Allosaurus
Velociraptor
Robin
Archaeopteryx
Sinornis
Theropods
Feathers with Flight feathers;
3-toed
foot;
Down
Light bones
arms as long
shaft, veins,
wishbone feathers
as legs
and barbs
17.2 Fan Models

Fan models can be used to show
either relative numbers of organisms
in a group, or be set up as a timeline
that shows the time of extinction of
organisms (or both)
• Organisms in the same ray (section of
the fan) share more characteristics
• They can be used to show connections
between extinct and current species
• An example is on pp. 454-455
Life’s Six
Kingdoms
17.2 Six Kingdoms

There are 6 kingdoms of organisms,
classified by differences in methods for
obtaining energy and cellular structures
•
•
•
•
•
•
Archaebacteria
Eubacteria
Protists
Fungi
Plants
Animals
17.2 Archaebacteria

Archaebacteria are types of prokaryotes
that:
• Are Unicellular
• Lack a membrane bound nucleus
• Are Autotrophic (photosynthetic and
chemosynthetic) and heterotrophic
• Includes several hundred species
• Generally live in oxygen-free, extreme
environments
• Have genes that are similar in structure to
eukaryotes
17.2 Eubacteria

Eubacteria are types of prokaryotes that:
• Are Unicellular
• Lack a membrane bound nucleus
• Are Autotrophic (photosynthetic and
chemosynthetic) and heterotrophic
• Includes 5000 species
• Have very strong cell walls
• Are sometimes helpful or harmful, but
generally harmless
• Live in most habitats, but not extremes
17.2 Protists

Protists are types of eukaryotes that:
• Lack complex organ systems
• Live in moist environments
• Have been around for up to 2 billion
years
• Can be unicellular or multi-cellular
• Can be plant-like, animal-like or funguslike
17.2 Fungi

Fungi are eukaryotes who:
• Are heterotrophs
• Do not move from place to place
• Can be unicellular or multi-cellular
• Absorb nutrients from organic materials
in the environment
• Have been around for over 400 million
years
• Have more than 50,000 different
species
17.2 Plants

Plants are photosynthetic eukaryotes who:
• Are multi-cellular
• Do not move from place to place
• Usually contain chloroplasts and have cell walls
made of cellulose
• Have cells organized into tissues, then organs,
then organ systems
• Are over 400 million years old

Scientists believe they are much older since plants do
not fossilize well
• Have over 250,000 known species
17.2 Animals

Animals are eukaryotes who:
• Are multi-cellular
• Are heterotrophs
• Can move from place to place
• Have cells without cell walls
• Have cells organized into tissues, then
organs, then organ systems
• Have existed for about 600 million years