Embed Size (px)
Citation preview
Chapter 18 2010 1
Classification of Organisms
Biology- Chapter 18 (508-533)Modern Bio Chapter 17 (336-351)
Biology Concepts and Connections Chap 15 (304-310)
Web cd 15c
18.1 Finding Order in Diversity18.2 Modern Evolutionary Classification18.3 Building the Tree of Life
Chapter 18 2010 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
Chapter 18 2010 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
Chapter 18 2010 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
Chapter 18 2010 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 taxa1. animals-land, air, or water, 2. Plant- based on stemsAs it progresses they realized it was not
working well
Chapter 18 2010 6
Linnaean SystemCarolus 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?
Chapter 18 2010 7
Chapter 18 2010 8
Levels of Classification pg1079
1. Domains- prokaryotes or eukaryotes- Eukarya
2. Kingdom- animals or plants- Animalia
3. Phyla (animals) or divisions (plants) Chordata
4. Classes-Mammalia
5. Orders- Carnivora
6. Family- Felidae
7. Genus- Felis
8. Species (Felis catus, domestic cat)
Chapter 18 2010 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
Binomial NomenclatureThe 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.
10Chapter 18 2010
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.
11Chapter 18 2010
Chapter 18 2010 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.
Chapter 18 2010 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
Evolutionary ClassificationWhat 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.
14Chapter 18 2010
Chapter 18 2010 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
Chapter 18 2010 16
Chapter 18 2010 17
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.
18Chapter 18 2010
Chapter 18 2010 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
Chapter 18 2010 20
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!
21Chapter 18 2010
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.
22Chapter 18 2010
Reading Cladograms
– This cladogram shows a simplified phylogeny of the cat family.
23Chapter 18 2010
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!
24Chapter 18 2010
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.
25Chapter 18 2010
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.
26Chapter 18 2010
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.
27Chapter 18 2010
Chapter 18 2010 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.
Chapter 18 2010 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.
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.
30Chapter 18 2010
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.
31Chapter 18 2010
Chapter 18 2010 32
Chapter 18 2010 33
1. Domains: Bacteria, Archaea, Eukarya
2. Kingdoms
a. Eubacteria
b. Archaebacteria
c. Protista
d. Fungi
e. Plantae
f. Animalia
The Tree of All Life
34Chapter 18 2010
Chapter 18 2010 35
Chapter 18 2010 36
Chapter 18 2010 37
Chapter 18 2010 38
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.
–
39Chapter 18 2010
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.
40Chapter 18 2010
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.
41Chapter 18 2010
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.”
42Chapter 18 2010
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.
43Chapter 18 2010
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.
44Chapter 18 2010
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.
45Chapter 18 2010
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.
46Chapter 18 2010
