1. CHAPTER 18 CLASSIFICATION

2. SECTION 1 FINDING ORDER IN DIVERSITY

3. KEY CONCEPT QUESTIONS:
How are living things organized for study?
What is binomial nomenclature?
What is Linnaeus’s system of classification?

4. How are living things organized for study?
To study the diversity of life, biologists use a classification system to name organisms and group them in a logical manner

5. Taxonomy is the science of naming and classifying organisms.
White oak: Quercus alba
A taxon is a group of organisms in a classification system.

6. Classification System to organize all living creatures plants animals
microbes
etc.

7. Why not use common names?
Misleading
starfish
dragonfly
Confusing
blue jay, blue coat, corn thief
dog, perro, chien
I swim, but I’m still a bird!

8. Why not use common names?
But they all have only one scientific name!
Pisaster ochraceus
Pyrrhosoma nymphula
Cyanocitta cristata

9. Some species have very similar common names.
Scientific names help scientists to communicate.
Some species have very similar common names.
Some species have many common names.

10. A more universal way of scientifically classifying came about
Binomial nomenclature is a two-part scientific naming system.
uses Latin words
scientific names always written in italics
two parts are the genus name and species descriptor

11. Carolus Linnaeus The Linnean system proposed in 1700s
each species has a 2 part name
genus
species
Homo sapiens

12. A genus includes one or more physically similar species.
Species in the same genus are thought to be closely related.
Genus name is always capitalized.
A species descriptor is the second part of a scientific name.
always lowercase
always follows genus name; never written alone
Tyto alba

13. The grizzly bear is called Ursus arctos.
The first part of the scientific name—in this case, Ursus—is the genus to which the organism belongs
The second part of a scientific name—in this case, arctos—is unique to each species within the genus (this is usually a Latin name)

14. Genus groupings Leopard Panthera pardus African lion Panthera leo
Tiger Panthera tigris

15. Linnaeus’ classification system has seven levels.
Each level is included in the level above it.
Levels get increasingly specific from kingdom to species.

16. Classification Kings Kingdom Play Phylum Chess Class Order On Family
Funny
Green
Squares
Kingdom
Phylum
Class
Order
Family
Genus
species

17. Orders & families

18. The Linnaean classification system has limitations.
Linnaeus taxonomy doesn’t account for molecular evidence.
The technology didn’t exist during Linneaus’ time.
Linnaean system based only on physical similarities.

19. KEY CONCEPT QUESTIONS:
How are living things organized for study?
Taxonomic categories
What is binomial nomenclature?
2-part universal naming system
What is Linnaeus’s system of classification?
each species has a 2 part name
genus
species

20. SECTION 2 MODERN EVOLUTIONARY CLASSIFICATION

21. KEY CONCEPT QUESTIONS:
How are evolutionary relationships important in classification?
How can DNA and RNA help scientists determine evolutionary relationships?

22. Physical similarities are not always the result of close relationships.
Genetic similarities more accurately show evolutionary relationships.
The red panda has given scientists taxonomic fits. It has been classified as a relative of the giant panda, and also of the raccoon, with which it shares a ringed tail. Currently, red pandas are considered members of their own unique family—the Ailuridae.

23. With the help of newer technology scientists have found more accurate ways of classifying organisms
Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical similarities.
In other words, species placed within the same genus should be more closely related to one another than to species of any other genus

24. EVOLUTIONARY CLASSIFICATION
method of grouping organisms together according to their evolutionary history
To refine the process of evolutionary classification, many biologists now prefer a method called cladistic analysis

25. Cladistics is classification based on common ancestry.
Phylogeny is the evolutionary history for a group of species.
evidence from living species, fossil record, and molecular data
shown with branching tree diagrams

26. Cladistics is a common method to make evolutionary trees.
classification based on common ancestry
species placed in order that they descended from common ancestor

27. A cladogram is an evolutionary tree made using cladistics.
A clade is a group of species that shares a common ancestor.
Each species in a clade shares some traits with the ancestor.
Each species in
a clade has traits
that have changed.

28. basis of arranging species in cladogram
Derived characters are traits shared in different degrees by clade members.
basis of arranging species in cladogram
more closely related species share more derived characters
represented on cladogram as hash marks
FOUR LIMBS WITH DIGITS
Tetrapoda clade 1
Amniota clade 2
Reptilia clade 3
Diapsida clade 4
Archosauria clade 5
EMBRYO PROTECTED BY AMNIOTIC FLUID
OPENING IN THE SIDE OF THE SKULL
SKULL OPENINGS IN FRONT OF THE EYE & IN THE JAW
FEATHERS & TOOTHLESS BEAKS.
SKULL OPENINGS BEHIND THE EYE
DERIVED CHARACTER

29. Molecular evidence reveals species’ relatedness.
Molecular data may confirm classification based on physical similarities.
Molecular data may lead scientists to propose a new classification.
DNA is usually given the last word by scientists.

30. The more similar the DNA sequences of two species, the more recently they shared a common ancestor, and the more closely they are related in evolutionary terms
Comparisons of DNA can also be used to mark the passage of evolutionary time.

31. Molecular clocks use mutations to estimate evolutionary time.
Mutations add up at a constant rate in related species.
This rate is the ticking of the molecular clock.
As more time passes, there will be more mutations.
DNA sequence from a
hypothetical ancestor
The DNA sequences from two
descendant species show mutations
that have accumulated (black).
The mutation rate of this
sequence equals one mutation
per ten million years.
Mutations add up at a fairly
constant rate in the DNA of species that evolved from a common ancestor.
Ten million years later—
one mutation in each lineage
Another ten million years later—
one more mutation in each lineage

32. Scientists estimate mutation rates by linking molecular data and real time.
an event known to separate species
the first appearance of a species in fossil record

33. Modern Systematics Shaking up some trees!
Crocodiles are now thought to be closer to birds than other reptiles

34. KEY CONCEPT QUESTIONS:
How are evolutionary relationships important in classification?
evolutionary history of a species based on common ancestries inferred from
fossil record
morphological & biochemical resemblances
molecular evidence
How can DNA and RNA help scientists determine evolutionary relationships?
The more similar the DNA sequences of two species, the more recently they shared a common ancestor, and the more closely they are related in evolutionary terms

35. SECTION 3 KINGDOMS AND DOMAINS

36. KEY CONCEPT QUESTIONS:
What are the six kingdoms of life as they are now identified? 
What is the three-domain system of classification?

37. Classification is always a work in progress.
The tree of life shows our most current understanding.
New discoveries can lead to changes in classification.
1866: all single-celled organisms moved to kingdom Protista
Until 1866: only two kingdoms, Animalia and Plantae
1938: prokaryotes moved to kingdom Monera
1959: fungi moved to own kingdom
1977: kingdom Monera split into kingdoms Bacteria and Archaea
Animalia
Protista
Fungi
Plantae
Archea
Bacteria

38. The three domains in the tree of life are Bacteria, Archaea, and Eukarya.
Domains are above the kingdom level.
proposed by Carl Woese based on rRNA studies of prokaryotes
domain model more clearly shows prokaryotic diversity

39. KEY CONCEPT QUESTIONS:
What are the six kingdoms of life as they are now identified? 
bacteria, archea, protista, fungi, plantae, and animalia
What is the three-domain system of classification?
Bacteria
Archea
Eukarya