Chapter 17 Classification

1. Chapter 17 Classification Information from Holt Biology & other sites as listed

2. Why is classification necessary?

3. Are you an organized person? • Consider – do you organize your room? Your clothes? Your school work? CDs? • What would happen if nothing was organized? • Would you be able to find anything?

4. Scientists have identified more than 2 MILLION SPECIES!!! • Every year, thousands of new species are discovered. • There may be millions of undiscovered species • especially microbes, plants & insects • In the Tropical Rain Forest & Oceans Classification helps scientists understand & study living things.

5. I. Biodiversity • Biodiversityis the variety of organisms on the earth. • Considered at all levels from populations to ecosystems.

6. A. Taxonomy • Taxonomyis the science of describing, naming, and classifying organisms. • The branch of biology that names & groups organisms -according to their characteristics & evolutionary history. • A Universal System was designed to Eliminate the use of Common Names and Confusion in the Scientific World.

7. The History of Taxonomy Aristotle – a Greek philosopherwho lived more than 2,000 years ago • Classified things- Plant or Animal • Grouped Animals into Land Dwellers, Water Dwellers, and Air Dwellers. • Also grouped Plants into 3 categories, based on differences in their Stems.

8. Aristotle’s classification system was replaced • As modern science Aristotle's system was found to be INADEQUATE. • Aristotle's categories did not work for all organisms. • his use of common names was problematic.

9. Use of Common Names • COMMON NAMES, such as “robin” or “fir tree”, for organisms created some problems • common names varied from one locale to next & did not describe species accurately. Use of long Latin names • Used by scientists before 1700’s,- did not show relationships between species & were inconvenient, hard to understand.

10. Describe a problem with each of these common names : -Starfish -Seahorse -Jelly fish -Peanut -Catfish -Tiger shark How are their names misleading? Discuss problems when 1 organism has 2 common names: Example- firefly & lightening bug

11. Carl Linnaeus (1707-1778) “Father of Modern Taxonomy” • He used morphology (which is the organism’s structure & form) • Grouped organisms into hierarchical categories

12. Carl Linnaeus • Formed “Taxa” (groups of organisms) • (Used Latin for the Names because it was the language of educated people) • Morphology -the STRUCTURAL SIMILARITIES BETWEEN ORGANISMS • Series of hierarchical categoriesused to show relationships • He had 2 KINGDOMS: PLANTAE & ANIMALIA.

13. B. Modern classification system is based on morphological similarities. • Hierarchy of eight groups (Taxa) • Domains- include all six kingdoms • Kingdom – a taxon of similar phyla or divisions • Phylum – (phyla-plural)- taxon of similar classes • Class – taxon of similar orders • Order – taxon of similar families • Family – group of similar genera • Genus – group of similar species • species – most exclusive, specific group. Members of this grouping can mate, produce viable offspring • (varieties)– same species but with slight differences • (subspecies) – same species, different location

14. 8 Modern Levels of Classification (From the most general to the most specific) • Domain • Kingdom • Phylum • Class • Order • Family • Genus • Species Species- is the smallest, most specific group- contains only 1 kind of organism. You need to know these!

15. Taxon - A particular group in a taxonomic system Most specific Taxon (group) Most general taxon

16. Pneumonic Devicespick one to help you remember the taxa • Keep Penguins Cool Or Find Good Shelter or • Kennywood Park Can Open For Good Summers. or • King Phillip Comes Over For Good Spaghetti

18. Classification Hierarchy of Organisms

19. 3 Domains: (Most modern level by scientist Carl Woese) • These are Broad groups above the kingdom level. Archaea Bacteria Eukarya

20. Binomial Nomenclaturemeans Two Name Naming • Uses the last 2 categories (the most specific) to name things. uses the Genus & Species for the 2 parts of the name • Always Capitalize the Genus but Not the Species Identifier. • Both are either underlined or italicized.

21. Using Binomial Nomenclature • Acer rubrum- RED MAPLE TREE • Acer is the Latin name for Maple (genus) • rubrum is the Latin word for Red(species) •   Can beAbreviated: A.rubrum. • Homo sapiens -HUMANS • Homo -large brain & upright posture. sapiensfor our intelligence & ability to speak. Abbreviated H. sapiens

22. Additional Categories • Zoologists • use term“SUBSPECIES”for variations that may occur in species from different geographical locations-ie, timber wolf and the northern timber wolf- ex Canis Lupus sspoccidentalis • Botanists • May use the term “division” instead of phylum • sometimes split species into Subsets known as VARIETIES.Example: peaches & nectarines are varieties of Prunuspersica var.

23. Additional Categories • Microbiologists- Bacteria are also broken into subsets called STRAINS. Example: Escherichia Coli – some strains are harmless, even helpful;- live in our intestines, but strain E. coli 157 is responsible for food poisoning deaths. According to the CDC there are an estimated 73,000 cases of E. Coli infection every year in the United States. The typical symptoms are bloody diarrhea and (if severe) kidney failure. These symptoms most commonly appear when a person has eaten undercooked or contaminated ground beef.

24. Testbook Assignment: • Read chapter 17, section 2 • do end of section questions • & Define: • Systematics • Phylogeny • Phylogenic Trees • Embryology, -blastula, -gastrula • Cladistics • derived characters, • cladogram

25. II. Systematics The way we group organismscontinues to changeToday these methods reflect the evolutionary history of organisms (What’s in their genes).This is called Phylogeny.

26. A. Phylogeny • organizes the diversity of living organisms in the context of evolution. • are based on several types of evidence: • Fossil Record • Morphology • Embryology • Chromosomes & Macromolecules

27. Phylogenic Trees • A family tree that shows evolutionary relationships thought to exist among organisms. • Is a hypothesis about the relationships. • Is subject to change - as more evidence is learned.

30. II. Evidences for Evolutionary Relationships 1. Fossil Record • a useful tool for ancient organisms. • Record is incomplete • Some organisms overrepresented • Some organisms may be missing • Need other evidences to verify phylogenic relationships

31. Fossils Types: actual preservation, petrification, imprints, molds, casts, footprints • Dated by radioactive isotopes in fossil or geological formation in which fossils are found • Requires long periods of time and unusual conditions for fossil preservation

32. II. Evidences for Evolutionary Relationships 2. Morphology • Examine structure & function • Homologousstructures-similar features that originated from similar ancestors. (forelimbs on bat, human, penguin) • Analogous structures-features that serve similar functions & look alike but originated from different embryonic tissues. (wings- on butterfly, bat, hummingbird) • Vestigial structures -serve no useful function any longer in the organism

33. Homologousstructures Comparing the structural features found in different organisms reveals a basic similarity. example is the forelimb of mammals - Although function is quite different, they are similar structurally.

34. Analogous structures • We must look at structures that look & function the same but are not derived from the same embryonic tissue. • These features do not show recent, related ancestory.

35. Vestigial structures • Features which serve no useful function any longer in the organism. • Examples: the pelvis bone in the whale, tailbone & appendix in humans, pelvis & leg bones in some snakes, etc

36. II. Evidences for Evolutionary Relationships Embryology • SIMILARITIES IN EARLY EMBRYOLOGICAL DEVELOPEMNT OF VERTEBRATES • CAN BE TAKEN AS ANOTHER INDICATION THAT VERTEBRATES MAY SHARE A COMMON ANCESTOR.

37. At the blastula stage, scientists begin to look for differences in the ways organisms develop.

38. Blastula - An early embryonic form produced by cleavage of a fertilized ovum - a spherical layer of cells surrounding a fluid-filled cavity.(think of a basketball) Gastrula -double-walled stage of the embryo succeeding the blastula; the outer layer of cells is the ectoderm and the inner layer differentiates into the mesoderm and endoderm

39. Embryology example- At the blastula stage- what happens if a scientist separates a cell from the ball? • In Vertebrates(animals with a backbone) & Echinodermsanimals like starfish & sand dollars)- any cell separated can produce a “twin”. • But blastula cells in a fruit fly cannot- the separated cells are already specialized to form a part & will die. • Conclusion- we are more closely related to starfish than insects

40. II. Evidences for Evolutionary Relationships 4. Chromosomes & Macromolecules • Taxonomists compare Macromolecules like DNA, RNA & Proteins. • Example- the number of differences in amino acids is a clue to how long ago 2 species “Diverged” • Divergent Evolution-2 species become more and more dissimilar. • Convergent Evolution-Species which have different ancestors, but have become more similar

41. Proteins indicate degree of relatedness. Differences - Amino Acids in Protein Cytochrome C • (From Atlas of Protein Sequence and Structure, 1967-68 by Margaret O. Dayhoff

42. Section 17.2 Summary – pages 450-459 Chromosome comparisons • For example, cauliflower, cabbage, kale, and broccoli look different but have chromosomes that are almost identical in structure.

43. Martin (1993).

44. B. Cladistics • uses shared, derived charactersas the only criterion for grouping taxa. • Shared character - A feature that all members of a group have in common • Derived character - A feature that evolved only within the group under consideration • is a newer way to display relationships

45. Derived Characters- are special features that apparently have only developed in that group. Examples: • feathers in birds • larger brains. Homosapiens have larger brains than the 'outgroup' (monkeys). The larger brain of homosapiens is a derived characteristic. • Clade – A Group of organisms that includes an ancestor plus all of its descendants

46. Cladogram • Diagrams which show derived characters • Shared & derived characters are strong indicators of common ancestry. • Cladograms can show non-traditional conclusions about which organisms are “close cousins”.

47. Cladogram

48. From this cladogram, we can figure out that brown bears have more derived characters in common with sun bears than with dogs & lesser pandas are more closely related to racoons than giant pandas.

49. Linnaean Taxonomy - compared to Phylogenetic Nomenclature: • Linnaean Taxonomy - Primary goal is to group species based on morphological similarities (who has 6 legs) • Phylogeny- Primary goal is to reflect the process of evolution(who’s close cousins)

50. Dichotomous Key • graphically organizes data. • You start with a main idea, split that into two major pieces. • Those pieces are then split again into two major pieces. You continue splitting until you reach only one possible answer. • Each set of questions is called a couplet, & contains instructions for which couplet to go to next.