Chapter 18

18.1 Finding Order in
By: Natalie Baumann
Assigning Scientific Names
• We assign scientific names
because each place in the
world has different names for
• Ex. in the UK the word
“Buzzard” means a hawk,
while in the US it means a
• A Swedish botanist came up
with a two word naming
system called binomial
nomenclature where each
species is assigned a two part
scientific name.
Classifying Species into Larger
• Scientists tried to classify
organisms into larger groups
that have a biological meaning
• This process of organizing living
thing is called systematics
The Linnaean Classification System
• Linnaeus found a way to group species
into taxa, or larger groups
• Over time his system expanded into seven
hierarchical taxa: Species, genus, family,
order, class, phylum, and kingdom with
kingdom being the most general and
encompassing all multicellular organisms,
and species being the most specific
Problems With Traditional Classification
• Over time systematics
have emphasized a
variety of differences
between those of the
same species
• There is already a
natural classification of
organisms determined
by with whom they mate
A branching diagram depicting the
successive points of species divergence
from common ancestral lines without
regard to the degree of deviation.
Evolution any process of formation
or growth; development: the
evolution of a language
Derived Character- trait that
appears in recent parts of a
lineage, but not in its ancestors
Common Ancestors
A clade- A group of species that
includes a single common ancestor
and all descendants of that ancestor

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