EVOLUTIONARY CLASSIFICATION

Sz2- Students will explain the evolutionary history of animals over the geologic history of Earth.

Geologic History Geologic time- time that began when earth was

formed until present day

http://geopolicraticus.files.wordpress.com/2009/12/geologic-time-scale.gif

200 Million Years Ago

150 Million Years Ago

100 Million Years Ago

50 Million Years Ago

Present

Evolution of the Earth with Time: Continental Drift

Important Terms Evolution- gradual change in a species over

time- sci. theory Theory-well-tested explanation that

explains a wide range of observations. Adaptation- any trait that helps an

organism survive and reproduce

Natural Selection- the process by which

individuals that are better adapted to their environment are more likely to survive and reproduce.

Charles Darwin

Natural Selection cont. Over a long time, natural

selection can modify a population enough to produce a new species

Helpful variations accumulate in a species while unfavorable ones disappear.

SpeciationWhen a group of individuals remain

separated from the rest of the species long enough to evolve different traits

How Speciation OccursGeographic isolation-

○ Pangaea /Continental Drift○ Landform isolation- river, mountain,

water. (ex. Squirrels of N. Grand Canyon)

Competition Gene flowEnvironmental change- local

adaptation to local environment

Speciation of Squirrels- Grand Canyon

The Kaibab squirrel (Sciurus aberti kaibabensis, left) became isolated in the Grand Canyon ~ 10,000 years ago. Features have gradually evolved that separate it from close relative, the Abert squirrel (S. aberti aberti)

A Problem with Traditional ClassificationExample: The Crab, The barnacle, & The limpet

• The barnacle and the limpet have similarly shaped shells & look alike

• The crab has a very different body form

• Based on anatomy, the barnacle & limpet could be classified together and the crab in a different group.

Related

This incorrect because crabs and barnacles are actually related

Crustaceans

Even though they do not look a like, crabs & barnacles are actually

related

Gastropods

Molted Exoskeleton

Segmentation

Free swimming Larva

A Problem with Traditional Classification

Traditional classification systems relied on body structure comparisons only

Due to convergent evolution, organisms that are quite different from each other evolve similar body structures.

Convergent Evolution: Process by which unrelated organisms independently evolve similarities when adapting to similar environments.

Modern Evolutionary Classification

Evolutionary Classification: Is the strategy of grouping organisms together based on their evolutionary history, instead of physical features.

Uses DNA and RNA, embryological development, comparative anatomy to classify species.

Modern Three-Domain System As scientists further analyzed cell structure and DNA , a

broader category was added- The domain is the most inclusive taxonomic category;

larger than a kingdom    The three domains are:

Bacteria : kingdom Eubacteria

Archaea,: kingdom Archaebacteria;

Eukarya :Kingdom Protista, Fungi, Plantae, and Animalia.

If these three species belong to the same genus, they are descended from a common ancestor.

Genus species

Felis

domestica

leo

margarita Sand cat`

Lion

Domestic Cat

Felis domestica

Felis leo

Felis margarita

Classification Using CladogramsCladogram: A diagram that shows theevolutionary relationships among a group of organisms.

Derived trait- new traits that show up in a lineage ex. jaws, lungs, mammary glands

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Modern Evolutionary Classification

Molecular Clocks

A model known as a molecular clock uses DNA comparisons to estimate the length of time that two species have been evolving independently.

Comparison reveals more DNA in common, the more recent the common ancestor

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Terminology Classification

Assigning organisms to different catagories based on their relationship

Taxonomy The science of naming

organisms Systematics

Determining evolutionary relationships of organisms

Phylogeny Evolutionary history

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Phylogenetic Tree Shows evolutionary

relationships More historical than

cladogram

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Myxozoa

Arthropoda AnnelidaMollusca

Lophophorates

Hemichordata

Chordata

Other pseudocoelomates

Nematoda

Porifera

CtenophoraCnidaria

Placozoa

PlatyhelminthesNemertea

CiliophoraSarcomastigophora

MicrosporaApicomplexa

Mesozoa

Echinodermata

CrustaceaChelicerata

Uniramia

Protochordates

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Birds MammalsReptile

AmphibianFish

Four LimbsAmniotic Egg

EndothermicFur

Feathers

Vertebrae

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Monophyletic groups (Clades)

A group of all the descendants of a common ancestor

The common ancestor is in the group

Example: Birds and ReptilesAncestor was a bird

like reptile

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Polyphyletic group that has some

similarities Contains organisms that

have not descended from a common ancestor

Based on physical characteristics instead of evolutionary evidence

Example: Flying vertebrates- pterosaurs, birds, mammals

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Cladogram Shows Evolutionary

relationships of a group of organisms

Each clad (group) share something in common

Ancestral traits are the oldest

Derived traits evolved later

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Cladogram for Transportation

Wheels are the most ancestral

Wings are the most derived

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Construct a Cladogram

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Gorilla Four limbs Fur Lost tail

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Tiger Four limbs Fur Tail

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Lizard Four limbs Tail

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Fish Tail

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Chimpanzee Four limbs Fur Lost tail

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Clad With 4 Limbs

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Clad With Fur

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Clad With No Tail

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Characteristics for Constructing Cladogram Tail is the most ancestral Four limbs is the oldest derived trait Fur is a later derived trait Loss of tail is the most derived trait

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Gorilla ChimpanzeeTiger

LizardFish

Four LimbsFur

Tail Lost

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Gorilla Tail? How do we know the

gorilla lost its tail?

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Gorilla’s Vestigial Tail

Gorilla Human

The End.