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 discoveredWhy Classify?• To study the diversity of life, biologists use a classification system to name organsisms and group them in a logical mannerTaxonomy - _____________________________________________________________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 countryEx.)• Scientists use Latin and Greek for scientific namesEarly 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 withdeeply divided leaves that have no hairs on their undersides and no teeth around theiredges.”Binomial Nomenclature• Carolus Linnaeus (18th Century)• Swedish Botanist• Developed a system for naming organismsBinomial Nomenclature - ___________________________________________________
Rules for Binomial Nomenclature1.2.3.Ex.) Genus species or Genus species or G. species• The name often tells you something about the speciesEx.) Tyranosaurus RexLinnaeus’s System of ClassificationTaxon (taxonomic category) - _______________________________________________________________________________________________________________________• Linnaeus’s system of classification uses seven taxonomic categories
Mnemonic DeviceK______________________ K _______________________P______________________ P________________________C______________________ C________________________O______________________ O________________________F______________________ F________________________G______________________ G________________________s_______________________ s ________________________
Name _________________________________ Date _____________________ Per ____ 18 -1 Section Review1. 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?
18 -2 Modern Evolutionary Classification• Back in Linneaus’s time when classifying organisms he compared structures and details of anatomyProblems 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 similaritiesClassification 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
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 classificationEx.) Myosin in humans & yeast
Molecular Clocks• Comparison of DNA can also be used to mark the passage of evolutionary timeMolecular 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
Name _________________________________ Date _____________________ Per ____ 18 -2 Section Review1. How is information about evolutionary relationships useful in classification?2. How are genes used to help scientists classify organisms?
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 informationThe 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
The Old 5 Kingdom System for Classification126.96.36.199.5.• In recent years, as evidence about microorganisms continued to accumulate, biologists come to recognize that the Monera were composed of two distinct groupsThe New 6 Kingdom System for Classification188.8.131.52.5.6.
The Three Domain System• Molecular analysis has given rise to a new taxonomic category that is now recognized by many scientistsDomain - _______________________________________________________________3 Domains1. o2. o3. oDomain BacteriaImportant Characteristics•• Prokaryotic - __________________________________________________________•••• Some photosynthesize• Some need oxygen o Aerobic - ______________________________________________________• Some don’t need oxygen o Anerobic - _____________________________________________________Domain ArchaeaImportant Characteristics•••• Live in extreme environmentsEx.)
Domain Eukarya• Consists of all organisms that have a ___________________________ProtistaImportant Characteristics••• eukaryotic - __________________________________________________________• cannot be classified as animals, plants or fungi, but share many characteristics with plants, animals and fungiPlant Like Protists•• Photosynthetic - _______________________________________________________Animal Like Protists•• heterotrophic - ________________________________________________________Fungus Like Protists••FungiImportant 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
Name _________________________________ Date _____________________ Per ____ 18 -3 Section Review1. 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?