18.1-Finding Order in Diversity
A scientific system is necessary to identify and organize the
overwhelming diveristy of life.
Taxonomy-naming/classifying
Scientific name=1 org only
Universal
Common names confusing
-1 sp can have diff. names
-2 sp can have same name
Binomial nomenclature

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
Linnaeus 1700s
2 parts: Genus &
species
Italics/underline
Can describe organism
Assigning Scientific Names p. 510
Taxonomy - the classification of all organisms based on shared
characteristics and changes as new discoveries are made.

Universal rules are necessary for identifying and naming
each species

A scientific name refers to only 1 organism

Common names are confusing (ex. Figure 18-1)
Ex. Same species can have different names
Scientific name: Felis concolor
Common names: cougar, puma, panther,mountain lion
Ex. Different species can have the same name
A "buzzard" refers to a hawk in the UK and a vulture in the US
Binomial Nomenclature

a two-part scientific name (Genus & species)
Swedish Botanist Carolus Linnaeus developed in 1730s

Scientific names should be italicized in print or underlined
when writing

Always capitalize the genus name, but write the species in
lower case

Ex. man is Homo sapiens

The genus name may be abbreviated, but not the species
(H. sapiens)
The species often describes an important trait of the organism or
its habitat
Taxonomy is a system for naming and classifying organisms. Universal rules
help scientists name organisms consistently by giving each organism a genus
name and a unique species name to prevent confusion caused by common
names which can be different in different regions. The scientific name is the
organism’s genus and species name and the species name may describe the
organism.
Classifying Species into Larger Groups
Systematics-the science of naming and grouping organisms
Systematics-naming and
grouping based on ancestry
Goal: to organize living things into groups that have biological
meaning (based on ancestry)
organisms in a particular group are more similar to one another
than they are to organisms in other groups
Taxa=groups

groups are called "taxa"
II. The Linnaean Classification System p. 513
Linnaeus
K,P, C, O, F, G,s

Linnaeus organized species into taxa based on their
morphology (similar structure & function)

Original system had 4 levels, it has been expanded to 7 l
The 7 taxa from broadest to most specific are
--- Kingdom, Phylum, Class, Order, Family, Genus, & species
See Figure 18-5 on p. 514 for Camel Example
Linnaeus used morphology

Linnaeus organized species into taxa based on their
morphology (similar structure & function)

Original system had 4 levels, it has been expanded to 7 l
The 7 taxa from broadest to most specific are
--- Kingdom, Phylum, Class, Order, Family, Genus, & species
Modern taxonomy uses




Fossils
DNA/RNA
Chromosomes
Embryos
See Figure 18-5 on p. 514 for Camel Example
"New discoveries" that affect Modern Taxonomy

Similarities between living species and fossils

Similar Chromosomes

DNA and RNA (macromolecules)

Patterns of Embryonic Development
Modern scientists consider evolutionary relationships and place
organisms in groups in branching patterns that reflect how closely
members of the groups are related to each other.
Similarities ex. all vertebrate embryos all have tail & gill slits
18.2 Modern Evolutionary Classification
Darwin’s “tree of life” a new way to classify organisms
phylogeny—the study of how living and extinct organisms are related
to one another.
led to
Phylogenetic systematics (evolutionary classification)

groups species by lines of evolutionary descent, not
similarities and differences.

places organisms into higher taxa whose members are
more closely related to one another than they are to
members of any other group.
Clade* - a group of species that includes a single common ancestor
and all descendants of that ancestor—living and extinct.

must be a monophyletic group* -includes all species that are
descended from a common ancestor
Cladogram*-diagram that illustrates how groups of organisms are
related to one another by showing how evolutionary lines, or lineages,
branched off from common ancestors. See Figure 18-7

“Nodes” represents a shared common ancestor.

“Root,” represents the common ancestor shared by all
organisms on the cladogram

branching patterns indicate degrees of relatedness among
organisms.

Uses derived character(s)- trait that arose in the most recent
common ancestor of a particular lineage and was passed along
to its descendants.
Ex. Hair is a derived character for the clade Mammalia
See Figure 18-8
Clades vs. Traditional (Linnean) groups
Many traditional taxonomic groups form valid clades
Ex. Class Mammalia=clade Mammalia.
Ex. Class Reptilia = Clade Reptilia (includes birds)
DNA in Classification
Shared genes(DNA) can be treated as derived characters in cladistic
analysis.
and can be used to develop hypotheses about evolutionary
relationships.
The use of DNA characters in cladistic analysis has helped to make
evolutionary trees more accurate.