Classification Systems

Transcription

1 Classification Systems

2 Why Classify? Name organisms Group them in a logical manner

3 Taxonomy The science of classifying organisms and assigning each one a universally accepted name Scientific Naming Name consists of the Genus and species

4 Scientific Name Example: Red Maple (this is the common name) Acer rubrum (italicized or underlined) Acer, is the genus (the latin word for maple) rubrum is the species (rubrum is the latin word for red) Why is it important to have a scientific name and not just a common name?

5 Daddy long-legs Each different but called the same name in different parts of the world

6 Biological Classification Linnaeus developed this system and placed living things into levels of classification. Based his system on specific traits Includes more groups than older systems Each level is called a taxon (taxa)

7 Kingdom Phylum Class Order Family Genus Species Linnaeus Classification System

8 Use a mnemonic to help you King Phillip Came Over For Good Soup

9 Kingdom The largest group Contains several phyla

10 Example: Kingdom Animalia consumers, multicellular,eukaryotes (a) A sea star

11 Phylum Includes several classes Includes a large number of different organisms. The organisms share some important basic characteristics

12 Example: Phylum Chordata Includes mammals, birds, fishes, amphibians and reptiles What do these animals have in common?

13 Class A group of closely related orders Example: Mammalia (covered with fur, warmblooded, nurse their young)

14 Order Several families of similar organisms Example: Carnivora, includes cats, dogs, bears, etc. Carnivores are meat-eaters

15 Family Larger than a genus Contains several related genera Example: Lions, tigers, cheetahs (all catlike animals belong in the family Felidae)

16 Genus Species that share common characteristics Example: Felis (contains the common house cat as well as the cougar and puma. (Small cats.) Have similar teeth, feet, and claws

17 Species Population of organisms that share similar characteristics and that can breed with one another and produce fertile offspring Example: catus (a tame cat)

18 Kingdom When first introduced all phyla belonged to either the Kingdom Animalia or Plantae The scientific view of life was not as complex in Linnaeus s time

19 Early Classification Traits used to separate Animals from Plants Animals were mobile, used food for energy Plants were green and photosynthetic

20 Two Kingdoms were not enough to logically include all organisms

21 The Six-Kingdom System Animalia Plantae Fungi Yeast, mushrooms and molds Protista Many microorganisms Eubacteria Archaebacteria previously Monera (the bacteria) Monera was added in 1969 and lasted for 20 yrs.

22 The Three-Domain System The Domain is larger than a Kingdom Scientists have used molecular analyses to group organisms into domains

23 The Three Domains: Bacteria Archaea Eukarya

24 Domain - Bacteria Kingdom Eubacteria (Eu means true, also known as the common bacteria) Characteristics Prokaryote (no nucleus) Composition of cell wall different from archaebacteria Unicellular Autotroph or heterotroph or chemotroph (energy from chemicals) HONORS Contain peptidoglycan in cell wall Peptidoglycan is a sugar polymer. These bacteria are less complex and easier to treat.

25 Escherichia coli Streptococcus

26 Domain Archaea Kingdom Archaebacteria ( Archa means initial, also known as extreme bacteria) Characteristics Prokaryote More complex cell wall composition Unicellular Autotroph or heterotroph or chemotrophic (energy from chemicals)

27 Halophile s (salt loving bacteria) in the Sierra Navada (aerial view) Halophile bacteria in Lake Natron, Tanzania Thermophiles heat loving. Live near volcanoes. Mt.St Helens

28 Methanogens live with no oxygen make methane gas (natural gas or swamp gas)

29 Characteristics Domain Eukarya Kingdom Protista Eukaryote (contain a nucleus) Most unicellular (some multicellular) Autotroph or heterotroph

30 Amoeba Paramecium Giant Kelp Slime mold

31 Characteristics Eukaryote Domain Eukarya Kingdom Fungi Cell walls made of chitin Material that makes up exoskeleton of insects and arthropods. Most multicellular (some unicellular) heterotroph

32 Mushroom Yeast Only unicellular fungi

33 Characteristics Eukaryote Domain Eukarya Kingdom Plantae Have Cell walls Contain chloroplasts Multicellular autotroph

34 Mosses, and ferns Flowering plant

35 Characteristics Eukaryote Domain Eukarya Kingdom Animalia No cell walls or chloroplasts Multicellular heterotroph

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37 Problems with Classification Which characteristics are more important? Those we can see. Or those we can t Classifying only observable traits can pose problems

38 Think about it. Linnaeus tried to group organisms according to biologically important characteristics This was more than a century before Darwin s ideas about descent with modification.

39 What is the problem with classifying based on body structure comparisons? Barnacles and limpets would be grouped together The problem is which similarities and differences are most important?

40 Grouping based on the lines of evolutionary descent Darwin s theory of evolution changed the way biologists thought about classification Crabs and barnacles are more closely related and are grouped together. Organisms are grouped into categories that represent lines of evolutionary descent, not just physical similarities

41 Evolutionary Classification Phylogeny-the study of how living and extinct organisms are related to one another The strategy is to group organisms together based on their evolutionary history (evolutionary classification) Look at their evolutionary descent rather than similarities and differences

42 Evolutionary Classification Common Ancestors Phylogenetic systematics places organisms into higher taxa The larger a taxon is, the farther back in time its members shared a common ancestor.

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44 For example, the following are all in the same Kingdom Animal They are also in the same phylum - Chordata And the same class- Mammalia They are all related to one another, but their common ancestor is further back in time. (note their differences)

45 As you get to the Genus and Species level, organisms are very closely related to one another. Their common ancestor is more recent in time. Ursus arctos maritimus americanus Different Genus, further back the common ancestor Same Genus more closely related Vulpes vulpes corsac cana

46 Its like a family tree. All these people are related to the Queen. Those at the base of the trunk are more closely related. If you are at the top, your common ancestor is further back in time. Families on individual branches are closely related to one another.

47 Evolutionary Classification Classifying organisms according to these rules places them into groups called clades Clade is a group of species that includes a single common ancestor and all descendants of that ancestor living and extinct.

48 Cladograms A diagram that shows the evolutionary relationships among a group of organisms Evolution of the car

49 DNA and Classification Scientists use similarities in the genetic makeup of organisms to help determine classification. Red pandas and giant pandas used to be classified together with the raccoon due to some anatomical similarities. However, DNA studies reveal that the giant panda actually shares a more recent common ancestor with bears than with raccoons. So giant pandas have been reclassified with other bears. The red panda has its own family.

50 Similarities in DNA and RNA Similarities in DNA can be used to help determine classification and evolutionary relationships DNA of different organisms can be read and compared to trace the history of genes. They are useful because all organisms have either DNA or RNA