copyright cmassengale Chapter 17 Classification copyright cmassengale

copyright cmassengale Chapter 17 – The Tree of Life Day 1 copyright cmassengale

copyright cmassengale Taxonomy What is taxonomy? The science of classification Why should we classify organisms? Provides a way to organize unfamiliar organisms Provides a way to name organisms copyright cmassengale

copyright cmassengale Aristotle 2000 years ago, Aristotle was the first taxonomist Aristotle divided organisms into plants and animals. He subdivided them by their habitat (land, sea, or air dwellers) copyright cmassengale

copyright cmassengale Early Taxonomists John Ray, a botanist, was the first to use Latin for naming His names were very long descriptions telling everything about the plant copyright cmassengale

copyright cmassengale Carolus Linnaeus Father of Taxonomy (classification) Divided organisms on the basis of structure Created the 2-part system for naming and classifying organisms called binomial nomenclature. copyright cmassengale

Binomial Nomenclature Two words Language of Latin (it’s universal; whereas common names may be different) Genus species (capitalize the Genus, not the species) Must be underlined or italicized copyright cmassengale

Homo sapiens or Homo sapiens Look at the example above Notice the first word, Homo, is capitalized. The second is not. When writing a scientific name, always capitalize the genus only. Use italics or underlining to let others know it is a scientific name. By the way, Homo sapiens is a human! copyright cmassengale

copyright cmassengale More on Linnaeus Linnaeus also came up with a system for organizing different types of organisms. Linnaeus’s system of classification uses eight taxonomic categories… Each group or level of organization is called a taxonomic category or a taxon. copyright cmassengale

Classification Timeline 2 Kingdom system accepted until 1866 when Haeckel proposed moving all single-celled organisms to the kingdom Protista 1938 – Copeland argued that the prokaryotes deserved their own kingdom called Monera 1959 – Whittaker proposed that because of how they feed, fungi should be placed into their own kingdom 1977 – Woese revealed two genetically different groups of prokaryotes splitting Monera into two kingdoms, Bacteria and Archaea copyright cmassengale

Hierarchy-Taxonomic Groups BROADEST TAXON Domain Kingdom Phylum (Division – used for plants) Class Order Family Genus Species Genus and species are the two names used to identify specific organisms in the binomial system of classification. Division is used for plants. Most Specific copyright cmassengale

copyright cmassengale D K P C O F G S It helps to come up with a sentence using the first letter of each taxon to help you remember them. For example, Did King Phillip Come Over For Good Spaghetti? copyright cmassengale

3 Domain System Some scientists use a 3 domain system. Domains are BIGGER than kingdoms. Domains Kingdoms Bacteria Eubacteria Archaea Archaebacteria Eukarya Protista Fungi Plantae Animalia These 2 kingdoms used to be combined into one called “Monera”

copyright cmassengale Domains Broadest, most inclusive taxon Three domains Archaea and Eubacteria are unicellular prokaryotes (no nucleus or membrane-bound organelles) Eukarya are more complex and have a nucleus and membrane-bound organelles copyright cmassengale

THE 6 KINGDOMS EUBACTERIA ARCHAEBACTERIA PROTISTA FUNGI PLANTAE ANIMALIA

copyright cmassengale ARCHAEA Probably the 1st cells to evolve Live in HARSH environments Found in: Sewage Treatment Plants Thermal or Volcanic Vents Hot Springs or Geysers that are acid Very salty water (Dead Sea; Great Salt Lake) copyright cmassengale

copyright cmassengale ARCHAEAN copyright cmassengale

copyright cmassengale EUBACTERIA Some may cause DISEASE Found in ALL HABITATS except harsh ones Important decomposers for environment Commercially important in making cottage cheese, yogurt, buttermilk, etc. copyright cmassengale

Live in the intestines of animals copyright cmassengale

Domain Eukarya is Divided into Kingdoms Protista (protozoans, algae…) Fungi (mushrooms, yeasts …) Plantae (multicellular plants) Animalia (multicellular animals) copyright cmassengale

copyright cmassengale Protista Most are unicellular Some are multicellular Some are autotrophic, while others are heterotrophic Aquatic copyright cmassengale

copyright cmassengale Fungi Multicellular, except yeast Absorptive heterotrophs (digest food outside their body & then absorb it) Cell walls made of chitin copyright cmassengale

copyright cmassengale Plantae Multicellular Autotrophic Absorb sunlight to make glucose – Photosynthesis Cell walls made of cellulose Growth, with increases in size and number of cells, is part of development. Development involves many stages from conception until death. copyright cmassengale

copyright cmassengale Animalia Multicellular Ingestive heterotrophs (consume food & digest it inside their bodies) Feed on plants or animals copyright cmassengale

copyright cmassengale Dichotomous Keying Used to identify organisms Characteristics given in pairs Read both characteristics and either go to another set of characteristics OR identify the organism copyright cmassengale

Example of Dichotomous Key 1a Tentacles present – Go to 2 1b Tentacles absent – Go to 3 2a Eight Tentacles – Octopus 2b More than 8 tentacles – 3 3a Tentacles hang down – go to 4 3b Tentacles upright–Sea Anemone 4a Balloon-shaped body–Jellyfish 4b Body NOT balloon-shaped - 5 This does not mean they need to be classified in the same group. Maybe they only evolved similar body structures! These situations make it very difficult for scientists to classify! copyright cmassengale

Classification of Living Things Section 18-3 Classification of Living Things Go to Section:

copyright cmassengale Chapter 17 – The Tree of Life Day 2 copyright cmassengale

Problems with Traditional Classification During Linnaeus’s time, scientists classified organisms based on their physical appearance, but today we know that doesn’t always work! Example: dolphins -> fish or mammals? Remember, convergent evolution -> sometimes organisms that are different from each other evolve similar body structures, due to the change in the environment. copyright cmassengale

Evolutionary Classification Biologists now group organisms into categories that represent lines of evolutionary descent, not just physical features. Evolutionary classification – is the strategy of grouping organisms together based on their evolutionary history. copyright cmassengale

Traditional v/s Evolutionary Classification Conical Shells Appendages Crustaceans Gastropod Limpet Crab Barnacle Limpet Crab Barnacle Molted exoskeleton Segmentation Tiny free-swimming larva EVOLUTIONARY CLASSIFICATION TRADITIONAL CLASSIFICATION

Evolutionary relationships These provide clues and information about how species evolved. They are determined on basis of: Similarities in structure Breeding behavior Geographical distribution Chromosomes Biochemistry Evolutionary relationships

I. Structural Similarities: Imply that species are closely related and may have evolved from same ancestor Examples: Dandelions/Sunflowers Bobcat/Lynx II. Breeding Behavior: Patterns of reproduction and mating Frogs III. Geographical Distribution: Genetic similarities despite geographic isolation Galapagos Island Finches

IV. Chromosomal Comparisons: Species may look different but have chromosomes that are almost identical in structure Example: Cauliflower, Cabbage, Broccoli V. Biochemistry: Studying DNA sequences, proteins, nucleotides in different organisms If their DNA sequences and proteins are more alike, then probably the organisms are closely related.

Classification using Cladograms To refine evolutionary classification, biologists now prefer a method called cladistics. Cladogram – a diagram that shows the evolutionary relationships among a group of organisms; includes new characteristics that arise as lineages evolve. Characteristics that appear in recent parts of a lineage but not in its older members are called derived characters copyright cmassengale

Here is an example… Derived Characters

Now let’s see what you can do… Use the following derived characters to fill in the cladogram, above: Wings - 6 Legs Segmented Body - Dbl set of wings Jumping legs - Crushing Mouth parts Legs - Curly Antennae

Did you get it? Wings 6 Legs Crushing Mouthparts Segmented Body Curly Antennae Jumping Legs Double Set of Wings Wings 6 Legs Crushing Mouthparts Segmented Body

Now create your own Cladogram… First, look at the animals we are studying and establish which characteristics that they share & which are unique to each individual species. CELLS BACKBONE LEGS HAIR OPPOSABLE THUMB Slug Catfish Frog Tiger Human

Now you try drawing your own cladogram using the information in the chart….

How’d you do? Opposable Thumbs Hair Legs Backbone Cells