The document discusses the classification of living things from early systems developed by Linnaeus to modern phylogenetic classification based on evolutionary relationships. It explains key concepts like binomial nomenclature, dichotomous keys, derived characters, DNA evidence, and the six kingdom system as well as the three domain system with Archaea, Bacteria, and Eukarya. Classification seeks to organize life into groups that reflect evolutionary descent.

1. Classification

2. Assigning Scientific Names
• We must be able to describe and name
each species
• The name must refer to only one species
• Common names won’t work

3. Binomial Nomenclature
• Developed by Carolus Linnaeus
• Each species is assigned a two-part
scientific name
• Written in Italic
• The first word (genus) begins with a
Capitol letter, the second word is lower
case.
• Ursus arctos – brown bear

4. Dichotomous Key
• Used to Identify Organisms
• A series of paired statements used to
describe characteristics of an organism
– Usually describe the presence or absence of
a structure
http://dnr.wi.gov/org/caer/ce/eek/critter/watercritter/a

5. • The science of naming and grouping
organisms is systematics
• The goal of systematics is to organize living
things into groups that have biological
meaning or taxa.
• Examples are “teacher” or “bird”

6. Linnaean Classification System
• Linnaeus developed a classification
system that organized species into taxa
that formed a hierarchy or set ordered
ranks.
• It started with 4 levels but expanded to 8
taxa (groups) with time
• Species are grouped according to
anatomical similarities and differences

10. Evolutionary Classification
• The study of how living and extinct
organisms are related to one another is
phylogeny
• Phylogenetic systematics (evolutionary
classification) groups species into larger
categories that reflect lines of evolutionary
descent.

11. • A clade is a group of species that includes
a single common ancestor and all
descendants of that ancestor
• Must be monophyletic
– Include all species that are descended from a
common ancestor
– Does not include species that are not
descended from a common ancestor

12. Cladogram

13. Cladogram
• Links groups of organisms by showing
how evolutionary lines branched off of
common ancestors
• Links Clades together

14. Building Cladograms
– A speciation event, in which an ancestral
lineage branches into two new lineages, is the
basis for each branch point, or node. Each node
represents the last point at which the new
lineages shared a common ancestor.
– The bottom, or “root,” of the tree represents
the common ancestor shared by all organisms
on the cladogram.

15. Building Cladograms
– A cladogram’s branching patterns indicate
degrees of relatedness among organisms.
– Because lineages 3 and 4 share a common
ancestor more recently with each other than they
do with lineage 2, you know that lineages 3 and 4
are more closely related to each other than they
are with lineage 2.

16. Building Cladograms
– Likewise, lineages 2, 3, and 4 are more
closely related, in terms on ancestry, with
each other than any of them is to lineage 1.

17. Building Cladograms
– This cladogram represents current hypotheses
about evolutionary relationships among
vertebrates.
– Note that in terms of ancestry, amphibians are
more closely related to mammals than they are
to ray-finned fish!

18. Reading Cladograms
– This cladogram shows a simplified
phylogeny of the cat family.

19. Reading Cladograms
– The lowest node represents the last common
ancestor of all four-limbed animals—members
of the clade Tetrapoda.

20. Reading Cladograms
– The forks show the order in which various
groups branched off over the course of
evolution.

21. Reading Cladograms
– The positions of the derived characters on the
cladogram reflect the order in which those
characteristics arose in this lineage.
– The trait of four limbs, for example, appeared
before the trait of hair in the history of the cat’s
lineage.

23. Derived Characters
• A trait that arose in the most recent common
ancestor of a particular lineage and was passed
along to its descendants
• Whether or not a character is derived depends
on the level at which you’re grouping organisms.
Four limbs, for example, is a derived character
for the clade tetrapoda. Hair is a derived
character for the clade Mammalia, but four limbs
is not derived for mammals. If it were, only
mammals would have four limbs!

24. Derived Characters
– Specialized shearing teeth is a derived character for the
clade Carnivora—of which both the coyote and lion are
members. Neither hair nor four limbs is a derived
character for this clade.
– Retractable claws is a derived character for the clade
Felidae (the cats). Notice that lions have this trait, but
coyotes do not.

25. Losing Traits
– Because distantly related groups of
organisms can lose the same character,
systematists are cautious about using the
absence of a trait as a derived character.
– For example, both whales and snakes have
lost the tetrapod character of four limbs—but
they are not very closely related. Snakes are
members of the clade Reptilia, while whales
are members of the clade Mammalia.

26. DNA in Classification
• DNA has helped to make evolutionary
trees more accurate

28. Building the Tree of Life
• Linneaus classified everything as either an
animal or plant
• As biologists learned more about the world
the 2 kingdoms needed to be expanded

29. Kingdoms
• The kingdoms expanded into a total of 6
kingdoms
– Eubacteria
– Archaebacteria
– “protista”
– Fungi
– Plantae
– Animalia

31. Domain
• Largest and most
inclusive category
• 3 subcategories
– Archaea-
prokaryotic,first cells
on earth
– Bacteria-prokaryotic
cells
– Eukarya- eukaryotic
cells

32. Domain Bacteria
• Unicellular
• Prokaryotic
• Corresponds to kingdom Eukarya
• Contain Peptidoglycan in their cell walls

33. Domain Archaea
• Unicellular
• Prokaryotic
• Live in Extreme Environments
• Lack Peptioglycan

34. Domain Eukarya
• All Organisms that have a nucleus

35. Problem “protists”
• Catchall group of eukaryotes
– Everything that is not a fungi, plant or animal
• Do not form a single clade as they are not
all from the same origin
– Some are multicellular, some are unicellular,
some are photosynthetic, some are
heterotrophs

36. Fungi
• Heterotrophs
• Cell walls contain Chitin
• Feed on dead or decaying organic matter
• Can be unicellular or multicellular

37. Plantae
• Multicellular
• Heterotrophic
• Cell walls contain cellulose
• non-motile
• Photosynthesize using chlorophyll

38. Animalia
• Multicellular
• Heterotrophic
• No cell walls
• Most can move about for some part of
their life cycle
• Very diverse