Chapter 17

Classification copyright cmassengale 1

Chapter 17 – The Tree of Life

DAY 1

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Taxonomy

What is taxonomy?

The science of classification

Why should we classify organisms?

• Provides a way to unfamiliar organisms Provides a way to organisms organize name

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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)

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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

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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 .

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Binomial Nomenclature

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

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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!

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More on Linnaeus

Linnaeus also came up with a system for organizing different • types of organisms.

Linnaeus’s system of classification uses eight categories… Each group or level of category or a taxon . taxonomic organization is called a taxonomic

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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 10

Hierarchy-Taxonomic Groups

Domain Kingdom Phylum BROADEST TAXON (Division – used for plants) Class Order Family Genus Species Most Specific copyright cmassengale 11

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?

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3 Domain System

Some scientists use a 3 domain system. Domains are BIGGER than kingdoms.

These 2 kingdoms used to be combined into one called “

Monera

”

Domains

Bacteria Archaea Eukarya

Kingdoms

Eubacteria Archaebacteria Protista Fungi Plantae Animalia

• • Broadest Three

Domains

, most inclusive taxon • 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

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THE 6 KINGDOMS

EUBACTERIA ARCHAEBACTERIA PROTISTA FUNGI PLANTAE ANIMALIA

• • • Probably the Live in

ARCHAEA

1 HARSH st cells to evolve 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)

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ARCHAEAN

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• •

EUBACTERIA

Some may cause

DISEASE

Found in

ALL HABITATS

harsh ones except • • Important

decomposers

environment cottage cheese, yogurt, buttermilk, etc.

for Commercially important in making

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Live in the intestines of animals copyright cmassengale 19

Domain Eukarya is Divided

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into Kingdoms

Protista Fungi (protozoans, algae…) (mushrooms, yeasts …) Plantae Animalia (multicellular plants) animals) (multicellular

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• • Most are unicellular Some are multicellular

Protista

• • Some are autotrophic , while others are heterotrophic Aquatic

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• Multicellular, except yeast

Fungi

• • Absorptive heterotrophs ( digest food outside their body & then absorb it ) Cell walls made of chitin

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• Multicellular

Plantae

• • • Autotrophic Absorb sunlight to make glucose – Photosynthesis Cell walls made of cellulose

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Animalia

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Multicellular Ingestive heterotrophs

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( consume food & digest it inside their bodies ) Feed on plants or animals copyright cmassengale 24

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Dichotomous Keying

Used to identify organisms Characteristics given in

pairs

Read both characteristics and either go to another set of characteristics OR identify organism the

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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!

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Go to Section:

Section 18-3 Classification of Living Things Things

Chapter 17 – The Tree of Life

DAY 2

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• • 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 from each other evolve environment.

similar -> sometimes organisms that are different body structures, due to the change in the

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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 .

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Traditional v/s Evolutionary Classification Appendages Conical Shells Crustaceans Gastropod Crab Barnacle Limpet Crab Barnacle Limpet

TRADITIONAL CLASSIFICATION

Molted exoskeleton Segmentation Tiny free-swimming larva

EVOLUTIONARY 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

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

• • IV. Chromosomal Comparisons: • Species may look different but have chromosomes that are almost identical in • 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 .

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Classification using Cladograms

To refine evolutionary classification, biologists now prefer a method called • • 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

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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:

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Wings - 6 Legs

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Segmented Body - Dbl set of wings

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Jumping legs

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Legs - Crushing Mouth parts - Curly Antennae

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

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.

Slug Catfish Frog Tiger Human CELLS BACKBONE LEGS HAIR OPPOSABLE THUMB

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

How’d you do?