2. 18 – 1 Finding Order in Diversity
• Evolution has lead to a staggering variety or organisms
• Biologists have identified and named about __________________________ species
so far
• They estimate anywhere between 2 and 100 million additional species have yet to be
discovered
Why Classify?
• To study the diversity of life, biologists use a classification system to name
organsisms and group them in a logical manner
Taxonomy - _____________________________________________________________
Assigning Scientific Names
• By the 18th century, European scientists recognized that referring to organisms by
common names was confusing
• Common names vary among regions within a country
Ex.)
• Scientists use Latin and Greek for scientific names
Early Efforts at Naming Organisms
• First attempts at standard scientific names often described physical characteristics
• As a result, these names could be 20 words long!
Ex.) The English translation of the scientific name of a particular tree might be “Oak with
deeply divided leaves that have no hairs on their undersides and no teeth around their
edges.”
Binomial Nomenclature
• Carolus Linnaeus (18th Century)
• Swedish Botanist
• Developed a system for naming organisms
Binomial Nomenclature - ___________________________________________________
3. Rules for Binomial Nomenclature
1.
2.
3.
Ex.) Genus species or Genus species or G. species
• The name often tells you something about the species
Ex.) Tyranosaurus Rex
Linnaeus’s System of Classification
Taxon (taxonomic category) - _______________________________________________
_______________________________________________________________________
_
• Linnaeus’s system of classification uses seven taxonomic categories
4. Mnemonic Device
K______________________ K _______________________
P______________________ P________________________
C______________________ C________________________
O______________________ O________________________
F______________________ F________________________
G______________________ G________________________
s_______________________ s ________________________
5. Name _________________________________ Date _____________________ Per ____
18 -1 Section Review
1. How are living things organized for study?
2. Describe the system for naming species that Linnaeus developed.
3. What are the seven taxonomic categories of Linnaeus’s classification system?
4. Why do scientists avoid using common names when discussing organisms?
5. Which category has more biological meaning—all brown birds or all hawklike birds?
Why?
6. 18 -2 Modern Evolutionary Classification
• Back in Linneaus’s time when classifying organisms he compared structures and
details of anatomy
Problems with Traditional Classification
• Sometimes, due to convergent Evolution organisms that are quite different from each
other evolve similar body structures
• Ex.)
Evolutionary Classification
• Darwin’s theory of evolution changed the entire way that biologists thought about
classification
• Biologists now group organisms into categories that represent
______________________________________________________, not just physical
similarities
Classification Using Cladograms
• Many biologists now prefer a method called _________________________________
• This method of classification identifies and considers only those characteristics that
arise as lineages evolve over time
7. Derived characteristics - ___________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Cladogram - _____________________________________________________________
_______________________________________________________________________
_
_______________________________________________________________________
_
Similarities in DNA and RNA
• Suppose you were trying to compare diverse organisms such as yeast and humans
• It wouldn’t make sense to try to classify anatomical similarities
• The genes of many organisms show important similarities at the molecular level
• These similarities can be used as criteria to help determine classification
Ex.) Myosin in humans & yeast
8. Molecular Clocks
• Comparison of DNA can also be used to mark the passage of evolutionary time
Molecular clock - _________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
__
• Mutations happen all the time at about the same rate
• A comparison of DNA sequences in two species can reveal how dissimilar the genes
are
• The degree of dissimilarity is an indication of how long ago the two species shared a
common ancestor
9. Name _________________________________ Date _____________________ Per ____
18 -2 Section Review
1. How is information about evolutionary relationships useful in classification?
2. How are genes used to help scientists classify organisms?
10. 3. What is the principle behind cladistic analysis?
4. Describe the relationship between evolutionary time and the similarity of genes in two
species.
5. have new discoveries in molecular biology affected the way in which we classify
organisms compared with the system used by Linnaeus?
18 -3 Kingdoms and Domains
• In taxonomy, as in all areas of science, ideas and models change as new information
arises, some explanations have been discarded altogether, whereas others such as
Darwin’s theory of evolution by natural selection, have been upheld
• So it should not be surprising that since the 1800’s, the tree of life has been revised
and edited since the discovery of all this new information
The Tree of Life Evolves
• Before Linnaeus’s time, the only two Kingdoms that existed were
_________________________________________________
• As scientists discovered new organisms that didn’t fit into the plant or animal
category, they made a new category
11. The Old 5 Kingdom System for Classification
1.
2.
3.
4.
5.
• In recent years, as evidence about microorganisms continued to accumulate,
biologists come to recognize that the Monera were composed of two distinct groups
The New 6 Kingdom System for Classification
1.
2.
3.
4.
5.
6.
12. The Three Domain System
• Molecular analysis has given rise to a new taxonomic category that is now recognized
by many scientists
Domain - _______________________________________________________________
3 Domains
1.
o
2.
o
3.
o
Domain Bacteria
Important Characteristics
•
• Prokaryotic - __________________________________________________________
•
•
•
• Some photosynthesize
• Some need oxygen
o Aerobic - ______________________________________________________
• Some don’t need oxygen
o Anerobic - _____________________________________________________
Domain Archaea
Important Characteristics
•
•
•
• Live in extreme environments
Ex.)
13. Domain Eukarya
• Consists of all organisms that have a ___________________________
Protista
Important Characteristics
•
•
• eukaryotic - __________________________________________________________
• cannot be classified as animals, plants or fungi, but share many characteristics with
plants, animals and fungi
Plant Like Protists
•
• Photosynthetic - _______________________________________________________
Animal Like Protists
•
• heterotrophic - ________________________________________________________
Fungus Like Protists
•
•
Fungi
Important Characteristics
•
• Ex.) Mushrooms, Yeast
o
• heterotrophs
• feed on ________________________________________________
• secrete digestive enzymes into food source then absorb the food into their bodies
• some are parasites
• spread and reproduce by _________________________
• Many are used in medicine
o
14. o
o
Plantae
Important Characteristics
•
• Photosynthetic autotrophs - ______________________________________________
_______________________________________________________________________
_
•
•
Animalia
Important Characteristics
•
• heterotrophic
•
•
• incredible diversity
15.
16. Name _________________________________ Date _____________________ Per ____
18 -3 Section Review
1. What are the six kingdoms of life as they are now identified?
2. What are the three domains of life?
3. Why was the kingdom Monera divided into two separate kingdoms?
4. Why might kingdom Protista be thought of as the “odds and ends” kingdom?
5. Which kingdoms include only prokaryotes? Which kingdoms include only
heterotrophs?
