Evolutionary Classification

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

Important Dates

4.6 billion years ago=Earth 3.8 bya = 1st LIFE2.0 bya= oxygen in atmosphere670 millions of years= 1st ANIMALS@500 mya= 1st FISH@365 mya=1st AMPHIBIANS@300 mya= 1st REPTILES@250 mya= DINOSAURS@200 mya= 1st MAMMALS@150 mya= 1ST BIRDS@100 mya= 1st primates@5 mya= 1st humans

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

physical feature comparisons only

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

environments.

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Modern Evolutionary Classification

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

Use DNA and RNA, embryological development, comparitive 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

Checkpoint1. When did the first animals appear in

geologic time? Humans?2. What is a theory?3. What is the process by which evolution

occurs?4. Why did traditional classification have

to change to evolutionary?5. What is the most inclusive taxonomic

category?

Classification Using CladogramsCladogram: A diagram that shows the evolutionary 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 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 Evolutionary

relationship of a group of organisms

Each clade (group) shares 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.