Classification Organizing Life’s Diversity

At least 1.7 million species of living organisms have been discovered At least 1.7 million species of living organisms have been discovered The list grows longer every year The list grows longer every year What should we do with them? What should we do with them? How are they to be classified? How are they to be classified?

18.1 Classification A. How classification begins 1. Biologists want to better understand organisms so they organize them. 2. One tool that they use to do this is classification a. the grouping of objects or information based on similarities.

18.1 Classification 3. Taxonomy is the branch of biology that groups and names organisms based their different characteristics.

1. The Greek philosopher Aristotle ( B.C.) developed the first widely accepted system of biological classification. 2. He classified all the organisms he knew into two groups: plants and animals. 3. According to his system, birds, bats, and flying insects are classified together even though they have little in common besides the ability to fly. B. Aristotle’s System

1. In the late eighteenth century, a Swedish botanist, Carolus Linnaeus ( ), developed a method of grouping organisms that is still used by scientists today. 2. Based on physical and structural similarities of organisms. 3. As a result, the groupings revealed the relationships of the organisms. C. Linnaeus’s System

4. Linnaeus developed a two-word naming system called binomial nomenclature to identify species. 5. Each species is assigned a two part scientific name. 6. Scientific names are always written in italics 7. The first word is capitalized and the second word is lowercase. Homo sapiens C. Linnaeus’s System

8. The first part of the scientific name is the genus 9. The second part of the scientific name is the species Do Ursus arctos and Ursus maritimus belong to the same species? To the same genus? C. Linnaeus’s System

10. Linnaeus’s hierarchical system of classification includes seven levels. 11. Each of these levels is called a taxon. From smallest to largest SpeciesGenusFamilyOrderClassPhylumKingdom C. Linnaeus’s System

12. Species – organisms that look alike and successfully interbreed ; the smallest and most specific of the taxonomic categories 13. Kingdom – the largest and most inclusive of the taxonomic categories C. Linnaeus’s System

D. Scientific and common names 1. Taxonomists are required to use Latin The language is no longer used in conversation and it does not change. Why do scientists use Latin names for classification? Because it is no longer used in conversation so it never changes Because it is no longer used in conversation so it never changes

Taxonomic Categories Kingdom (most broad)King Kingdom (most broad)King PhylumPhilip PhylumPhilip ClassCame ClassCame OrderOver OrderOver FamilyFor FamilyFor GenusGreen GenusGreen Species (most specific)Soup Species (most specific)Soup

Which taxon contains the others? A. A.Order B. B.Class C. C.Genus D. D.Family

F. Taxonomy: A useful tool 1. Remember taxonomy is the study of classifying organisms 2. Some biologists use a dichotomous key 3. A Dichotomous Key is made up of a set of paired numbered statements. Each set deals with a single characteristic of an organism, such as leaf shape or arrangement. 3. By following the key, a specific organism can be identified based on characteristics. Example: 1.a) Is the leaf simple? Go to 2 b) Is the leaf compound? Go to 3 2.a) Are margins of the leaf jagged? Go to 4 b) Are margins of the leaf smooth? Go to 5

What is a dichotomous key? A dichotomous key is a set of paired statements that can be used to identify organisms.

1. Physical characteristics 2. Behavioral – breeding behavior 3. Chromosomes 4. DNA/Biochemistry Evidence to Classify Organisms

1. Physical characteristics a. a. Structural similarities among species reveal relationships b. The presence of many shared physical structures implies that species are closely related and may have evolved from a common ancestor.

Evidence to Classify Organisms 2. Behavioral – breeding behavior a. Two species of frogs, Hyla versicolor and Hyla chrysoscelis live in the same area and look similar b. During the breeding season there is an obvious difference in their mating behavior – different pitch rate between the calls

Evidence to Classify Organisms 3. Chromosomes a. Both the number and structure of chromosomes, as seen during mitosis and meiosis, provide evidence about relationships among species. For example, cauliflower, cabbage, kale, and broccoli look different but have chromosomes that are almost identical in structure.

Evidence to Classify Organisms 4. DNA/Biochemistry a. Closely related species have similar DNA sequences and therefore proteins b. In general, the more inherited nucleotide sequences that two species share, the more closely related they are.

Which of the following is NOT a way to determine evolutionary relationships? A. DNA A. DNA B. Chromosomes B. Chromosomes C. Taxon C. Taxon D. Behavioral D. Behavioral

Biologists group organisms into categories that represent lines of evolutionary descent, or phylogeny, not just physical similarities The evolutionary history of a species is called its phylogeny. Evolutionary Classification

1. Cladistics – system of classification based on phylogeny a. Characteristics and organisms can be organized on a tree-like model b. Starts with a common ancestor c. Groups of organisms diverge from the ancestor d. Nodes are where the organisms branch off – these are anatomical relationships like backbones, tails, etc e. All of the organisms have the trait after the node f. Shown on a cladogram B. Phylogenetic Classification: Models

Theropods Allosaurus Sinornis Velociraptor Archaeopteryx Robin Light bones 3-toed foot; wishbone Down feathers Feathers with shaft, veins, and barbs Flight feathers; arms as long as legs Cladogram

14.2 The Six Kingdoms

Three main characteristics that distinguish the members of each kingdom a. Cellular type (complex or simple) b. Their ability to make food c. The number of cells in their body C. The Six Kingdoms of Organisms

What three main characteristics distinguish the members of the six kingdoms? Type of cell Type of cell How they obtain their food How they obtain their food Number of cells Number of cells

SIX KINGDOMS ARCHAEBACTERIA (Prokaryotes) ARCHAEBACTERIA (Prokaryotes) EUBACTERIA (Prokaryotes) EUBACTERIA (Prokaryotes) PROTISTS (Eukaryotes) PROTISTS (Eukaryotes) FUNGI (Eukaryotes) FUNGI (Eukaryotes) PLANTS (Eukaryotes) PLANTS (Eukaryotes) ANIMALS (Eukaryotes) ANIMALS (Eukaryotes)

Prokaryotic Kingdoms Prokaryotes - organisms with cells that lack a nuclei bounded by a membrane Prokaryotes - organisms with cells that lack a nuclei bounded by a membrane Originally the two bacteria were grouped together in one kingdom called Monera. Originally the two bacteria were grouped together in one kingdom called Monera. Now they are separated into two kingdoms: Archaebacteria and Eubacteria Now they are separated into two kingdoms: Archaebacteria and Eubacteria

Kingdom Archaebacteria A. Prokaryotic with cell walls 1. Unicellular 2. Chemotrophic, Autotrophic or Heterotrophic B. Found in extreme environments 1. Swamps, deep-ocean hydrothermal vents 2. Oxygen free environments Examples: halobacterium, methanogens and thermoacidophiles

Kingdom Eubacteria (Streptococcus pneumoniae) A. Prokaryotic with cell wall 1. Unicellular 2. Autotrophic or Heterotrophic B. Most species of bacteria are in this kingdom C. Live in most environments D. Some cause diseases 1. Strep throat and pneumonia E. Most are harmless and many may be helpful

Kingdom Protista (slime molds and algae) A. Eukaryotic with a cell wall 1. Most are unicellular, some are multicellular with cilia and flagella 2. Lacks complex organ systems 3. Autotrophic and/or Heterotrophic B. Lives in moist environments (pond water) C. Members are very different from one another 1. Some are plantlike (algae) 2. Some are animal-like (protozoa) 3. Some are fungus-like (slime molds)

Kingdom Fungi (mushrooms, mold and mildew) A. Eukaryotic with cell walls made of chitin 1. Most are multicellular, some are unicellular 2. External heterotrophs; decomposers

Kingdom Plantae (Ferms, Angiosperms) A. Eukaryotic with cell walls made of cellulose 1. All multicellular 2. Autotrophs and photosynthetic 3. No species can move from place to place. B. Second largest kingdom C. Range from tiny mosses to giant trees D. Use of chlorphyll for solar-energy transformation

Kingdom Animalia (Invertebrates and Vertebrates) A. Eukaryotic with no cell walls 1. Multicellular with complex cells 2. Heterotrophs with specialized organ systems B. Largest kingdom C. Nearly all are able to move from place to place.

Six Kingdoms Summary Kingdoms Archaebacteria and Eubacteria contain only unicellular prokaryotes. Kingdoms Archaebacteria and Eubacteria contain only unicellular prokaryotes. Kingdom Protista contains eukaryotes that lack complex organ systems. Kingdom Protista contains eukaryotes that lack complex organ systems. Kingdom Fungi includes heterotrophic eukaryotes that absorb their nutrients. Kingdom Fungi includes heterotrophic eukaryotes that absorb their nutrients. Kingdom Plantae includes multicellular eukaryotes that are photosynthetic. Kingdom Plantae includes multicellular eukaryotes that are photosynthetic. Kingdom Animalia includes multicellular, eukaryotic heterotrophs with cells that lack cell walls. Kingdom Animalia includes multicellular, eukaryotic heterotrophs with cells that lack cell walls.

Which of the following describes a fungus? A. autotrophic prokaryote B. unicellular or multicellular heterotroph C. unicellular autotroph D. heterotrophic prokaryote