Autotrophs capture the light energy from
sunlight and convert it to chemical
they use for food.
Heterotrophs must get energy by eating
autotrophs or other heterotrophs.
Decomposers, aka saprobes, are heterotrophs
that recycle dead organisms by breaking them
• Taxonomy is the science of grouping
and naming organisms.
• Classification the grouping of
information or objects based on
Why use a dead
•We only know about a fraction of the
organisms that exist or have existed on
•Taxonomists give a unique scientific name to
each species they know about whether it’s
today or extinct.
• The scientific name comes from one of two
“dead” languages – Latin or ancient Greek.
•There are at least 50 common names for
the animal shown on the previous 7 slides.
•Common names vary according to region.
•Soooo……why use a scientific name?
•a two name system for writing scientific names.
•The genus name is written first (always Capitalized).
•The species name is written second (never
•Both words are
italicized if typed or underlined if hand written.
Example: Felis concolor or F. concolor
Which is the genus? The species?
"Formal" scientific names should have a third
part, the authority.
The authority is not italicized or
The authority is written as an abbreviation of
the last name of the person responsible for
naming the organism. Since Carolus Linnaeus
was the first person to name many plants,
the L. for Linnaeus is very common in plant
An example is Quercus alba L.
Phylogeny, the evolutionary history of an
organism, is the cornerstone of a branch
of biology called systematic taxonomy.
Systematics, as systematic taxonomy is
commonly called, is the study of the
evolution of biological diversity.
A phylogenetic tree is a family tree
that shows a hypothesis about the
evolutionary relationships thought
to exist among groups of organisms.
It does not show the actual
evolutionary history of organisms.
Why a hypothesis?
Phylogenetic trees are usually based
on a combination of these lines of
Embryological patterns of
Chromosomes and DNA
Cladistics - is a relatively
new system of phylogenetics
classification that uses
shared derived characters to
relationships. A derived
character is a feature that
apparently evolved only within
the group under
There are three basic
assumptions in cladistics:
1.Organisms within a group are
descended from a common
2.There is a bifurcating pattern
3.Change in characteristics
occurs in lineages over time.
A phylogenetic tree based on a
cladistic analysis is called a
What derived character is shared by
all the animals on the cladogram on
the next slide?
The acacia and its
ants are an example
of coevolution. Each
influences the others
Can you think of any
other examples of
“instead of a slow, continuous movement,
evolution tends to be characterized by long
periods of virtual standstill ("equilibrium"),
"punctuated" by episodes of very fast
development of new forms”
The "punctuated equilibrium" theory of
Niles Eldredge and Stephen Jay Gould was
proposed as a criticism of the traditional
Darwinian theory of evolution…what is it
• A key is a device for easily and quickly
an unknown organism.
• The dichotomous key is the most widely
used type in biological sciences.
• The user is presented with a sequence of
choices between two statements, couplets,
based on characteristics of the organism. By
always making the correct choice, the name
of the organism will be revealed.
The Dichotomous Key
The Three Domains
• Domain Archaea
– Includes newly discovered cell types
– Contains 1 kingdom – the Archaebacteria
– Includes other members of old kingdom
– Has 1 kingdom – the Eubacteria
– Includes all kingdoms composed of organisms made
up of eukaryotic cells
The major classification levels,
from most general to most specific
(several of these have subdivisions)
A group at any level is a taxon.
Kingdoms are divided into groups called phyla
Phyla are subdivided into classes
Classes are subdivided into orders
Orders are subdivided into families
Families are divided into genera
Genera contain closely related species
Species is unique
Categories within Kingdoms