1. Classification of Organisms
Biology- Chapter 18 ( )
Modern Bio Chapter 17 ( )
Biology Concepts and Connections Chap 15 ( )
Web cd 15c
18.1 Finding Order in Diversity
18.2 Modern Evolutionary Classification
18.3 Building the Tree of Life
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2. Objectives Relate biodiversity to biological classification
Explain why naturalist replaced Aristotle's classification system
Identify the main criterion that Linnaeus used to classify organisms
List the common levels of modern classification from general to specific
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3. Biodiversity
Biologists have named and classified almost 2 million species. However, they estimated that the total number of species on Earth is much greater. Over time, Scientist have created various systems of classification to organize their knowledge of the tremendous number of species. Each system places species into categories bases on particular characteristics
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4. Classifying Organisms
biodiversity- the variety of organisms considered at all levels from populations to ecosystems
Continues to grow everyday  not complete
Erwin cataloging insects, over 1000 beetles, 30 million species of insects ww
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5. Taxonomy sciences of describing , naming, and classifying organisms
Taxon or taxa- group with in a taxonomic system
Aristotle, Greek philosopher, classified organisms into only 2 taxa
1. animals-land, air, or water,
2. Plant- based on stems
As it progresses they realized it was not working well
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6. Linnaean System Carolus Linnaeus, Swedish naturalist (1707-1778)
Developed a system of grouping organisms into hierarchical categories according to their form and structure
Simple to complex, 7 categories
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Did King Philip Come Over For Grape Soda
Can you do your own?
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8. Levels of Classification pg1079
Domains- prokaryotes or eukaryotes- Eukarya
Kingdom- animals or plants- Animalia
Phyla (animals) or divisions (plants) Chordata
Classes-Mammalia
Orders- Carnivora
Family- Felidae
Genus- Felis
Species (Felis catus, domestic cat)
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9. Binomial Nomenclature
Linnaeus gave organisms a species name or a scientific name that contained 2 parts
Linnaeus grouped species according to anatomical similarities and differences.
2 Parts:
1. genus: Homo
2. species identifier: sapiens
Species name is written in italics and the genus name capitalized, tend to come from Latin roots
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10. Binomial Nomenclature
The polar bear, for example, is called Ursus maritimus.
The first part of the name—Ursus—is the genus to which the organism belongs. A genus is a group of similar species. The genus Ursus contains five other species of bears, including Ursus arctos, the brown bear or grizzly bear.
The second part of a scientific name—maritimus for polar bears—is unique to each species and is often a description of the organism’s habitat or of an important trait. The Latin word maritimus refers to the sea: polar bears often live on pack ice that floats in the sea.
The scientific name of the red maple is Acer rubrum.
The genus Acer consists of all maple trees.
The species rubrum describes the red maple’s color.
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11. Problems With Traditional Classification
For example, adult barnacles and limpets live attached to rocks and have similar-looking shells.
Adult crabs don’t look anything like barnacles and limpets.
Based on these features, one would likely classify limpets and barnacles together and crabs in a different group. However, that would be wrong.
Modern classification schemes look beyond overall similarities and differences and group organisms based on evolutionary relationships.
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12. systematic
More than 200 years ago, Linnaeus grouped organisms according to similarities that he could readily see. Modern biologists consider not only visible similarities but also similarities in embryos, chromosomes, proteins, and DNA. In systematic, the goal is to classify organisms in terms of their natural relationships.
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13. objectives
Identify the kinds of evidence that modern biologists use in classifying organisms
Explain what information a phylogenetic diagram displays
State the criteria used in cladistic analysis
Describe how a cladogram is made
Explain cladistic taxonomy, and identify one conclusion that is in conflict with classical taxonomy
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14. Evolutionary Classification
What is the goal of evolutionary classification?
The goal of phylogenetic systematics, or evolutionary classification, is to group species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences.
The concept of descent with modification led to phylogeny—the study of how living and extinct organisms are related to one another.
Advances in phylogeny, in turn, led to phylogenetic systematics, or evolutionary classification. Phylogenetic systematics groups species into larger categories that reflect lines of evolutionary descent, rather than overall similarities and differences.
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15. Phylogenetics
The analysis of the evolutionary or ancestral relationships among taxa
Use phylogenetic diagram or tree
They can change due to new discoveries and investigations
Determine if any evidence of shared ancestry
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18. What is a Cladograms
A clade is a group of species that includes a single common ancestor and all descendants of that ancestor—living and extinct.
A clade must be a monophyletic group. A monophyletic group must include all species that are descended from a common ancestor, and cannot include any species that are not descended from that common ancestor.
A cladogram links groups of organisms by showing how evolutionary lines, or lineages, branched off from common ancestors.
Modern evolutionary classification uses a method called cladistic analysis to determine how clades are related to one another.
This information is used to link clades together into a cladogram, which illustrates how groups of organisms are related to one another by showing how evolutionary lines, or lineages, branched off from common ancestors.
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19. cladistic
System of phylogenetic analysis that uses shared and derived characters
Shared character- is a feature that all members of a group have in common, such as hair in mammals or feathers in birds
Derived character- feature that evolved only within the group under consideration, feathers evolved with in birds
Clad- group of organisms that includes an ancestor plus all of its descendants
Cladogram- chart developed
Fig 17.3
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21. 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!
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22. Derived Characters
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!
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.
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23. Reading Cladograms
This cladogram shows a simplified phylogeny of the cat family.
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24. Clades and Traditional Taxonomic Groups
Two clades do include the birds: clade Aves, (the birds themselves), and clade Reptilia. Therefore, according to cladistics, a bird is a reptile!
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25. New Techniques Suggest New Trees
The use of DNA characters in cladistic analysis has helped to make evolutionary trees more accurate.
For example, traditionally African vultures and American vultures were classified together in the falcon family.
Molecular analysis, however, showed that DNA from American vultures is more similar to the DNA of storks than it is to the DNA of African vultures.
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26. New Techniques Suggest New Trees
Often, scientists use DNA evidence when anatomical traits alone can’t provide clear answers.
For example, giant pandas and red pandas share many characteristics with both bears and raccoons.
DNA analysis revealed that the giant panda shares a more recent common ancestor with bears than with raccoons. Therefore, the giant panda has been placed in a clade with bears.
Red pandas, however, are in a clade with raccoons and other animals like weasels and seals.
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27. THINK ABOUT IT
The process of identifying and naming all known organisms, both living and extinct, is a huge first step toward the goal of systematics.
The real challenge, however, is to group everything—from bacteria to dinosaurs to blue whales—in a way that reflects their evolutionary relationships.
Over the years, new information and new ways of studying organisms have produced major changes in Linnaeus’s original scheme for organizing living things.
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28. Modern Classification
Biologist continue to develop taxomies to organize life’s enormous diversity. They regularly revise the many branches of the “tree of life” to reflect current hypotheses of the evolutionary relationships between groups. They have revised the larges and most fundamental categories of the Linnean-inspired classification system- domains and kingdoms.
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29. objectives
Describe the evidence that prompted the invention of the three-domain system of classification
List the characteristics that distinguish between the domains Bacteria, Archaea, Eukarya
Describe the 6-kingdom system of classification
Identify problematic taxa in the 6-kingdome system
Explain why taxonomic systems continue to change.
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30. Changing Ideas About Kingdoms
During Linnaeus’s time, living things were classified as either animals or as plants.
Animals were organisms that moved from place to place and used food for energy.
Plants were green organisms that generally did not move and got their energy from the sun.
As biologists learned more about the natural world, they realized that Linnaeus’s two kingdoms—Animalia and Plantae—did not reflect the full diversity of life.
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31. Changing Ideas About Kingdoms
Classification systems have changed dramatically since Linnaeus’s time, and hypotheses about relationships among organisms are still changing today as new data are gathered.
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33. Domains: Bacteria, Archaea, Eukarya Kingdoms a. Eubacteria
b. Archaebacteria
c. Protista
d. Fungi
e. Plantae
f. Animalia
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34. The Tree of All Life
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39. Domain Bacteria
Members of the domain Bacteria are unicellular and prokaryotic. This domain corresponds to the kingdom Eubacteria.
Their cells have thick, rigid walls that surround a cell membrane and contain a substance known as peptidoglycan.
These bacteria are ecologically diverse, ranging from free-living soil organisms to deadly parasites. Some photosynthesize, while others do not. Some need oxygen to survive, while others are killed by oxygen.
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40. Domain Archaea
The domain Archaea corresponds to the kingdom Archaebacteria.
Members of the domain Archaea are unicellular and prokaryotic, and they live in some extreme environments—in volcanic hot springs, brine pools, and black organic mud totally devoid of oxygen. Many of these bacteria can survive only in the absence of oxygen.
Their cell walls lack peptidoglycan, and their cell membranes contain unusual lipids that are not found in any other organism.
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41. Domain Eukarya
The domain Eukarya consists of all organisms that have a nucleus. It comprises the four remaining kingdoms of the six-kingdom system: “Protista,” Fungi, Plantae, and Animalia.
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42. The “Protists”: Unicellular Eukaryotes
The kingdom Protista has long been viewed by biologists as a “catchall” group of eukaryotes that could not be classified as fungi, plants, or animals.
Recent molecular studies and cladistic analyses have shown that “the eukaryotes formerly known as “Protista” do not form a single clade. Current cladistic analysis divides these organisms into at least five clades.
Since these organisms cannot be properly placed into a single taxon, we refer to them as “protists.”
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43. The “Protists”: Unicellular Eukaryotes
Most “protists” are unicellular, but one group, the brown algae, is multicellular.
Some “protists” are photosynthetic, while others are heterotrophic.
Some display characters that resemble those of fungi, plants, or animals.
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44. Fungi
Members of the kingdom Fungi are heterotrophs with cell walls containing chitin.
Most fungi feed on dead or decaying organic matter. They secrete digestive enzymes into their food source, which break the food down into smaller molecules. The fungi then absorb these smaller molecules into their bodies.
Mushrooms and other recognizable fungi are multicellular, like the ghost fungus shown. Some fungi—yeasts, for example—are unicellular.
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45. Plantae
Members of the kingdom Plantae are multicellular, have cell walls that contain cellulose, and are autotrophic.
Autotrophic plants are able to carry on photosynthesis using chlorophyll.
Plants are nonmotile—they cannot move from place to place.
The entire plant kingdom is the sister group to the red algae, which are “protists.” The plant kingdom, therefore, includes the green algae along with mosses, ferns, cone-bearing plants, and flowering plants.
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46. Animalia
Members of the kingdom Animalia are multicellular and heterotrophic.
Animal cells do not have cell walls.
Most animals can move about, at least for some part of their life cycle.
There is incredible diversity within the animal kingdom, and many species of animals exist in nearly every part of the planet.
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