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

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.

Speciation When a group of individuals remain separated from the rest of the species long enough to evolve different traits

How Speciation Occurs Geographic isolation- ○ Pangaea /Continental Drift ○ Landform isolation- river, mountain, water. (ex. Squirrels of N. Grand Canyon) Competition Gene flow Environmental 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 Classification Example: 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 Convergent Evolution : Process by which unrelated organisms independently evolve similarities when adapting to similar environments.

Modern Evolutionary Classification 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 Cladograms Cladogram Cladogram : A diagram that shows the evolutionary relationships among a group of organisms.

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 19

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 20

Phylogenetic Tree  Shows evolutionary relationships  More historical than cladogram 21

22 MyxozoaMyxozoa ArthropodaArthropoda AnnelidaAnnelida MolluscaMollusca LophophoratesLophophorates HemichordataHemichordata ChordataChordata OtherpseudocoelomatesOtherpseudocoelomates NematodaNematoda PoriferaPorifera CtenophoraCtenophora CnidariaCnidaria PlacozoaPlacozoa PlatyhelminthesPlatyhelminthes NemerteaNemertea CiliophoraCiliophora SarcomastigophoraSarcomastigophora MicrosporaMicrospora ApicomplexaApicomplexa MesozoaMesozoa EchinodermataEchinodermata CrustaceaCrustacea ChelicerataChelicerata UniramiaUniramia ProtochordatesProtochordates

23 Birds Mammals Reptile Amphibian Fish Four Limbs Amniotic Egg Endothermic Fur Feathers Vertebrae

Monophyletic groups (Clades)  A group of all the descendants of a common ancestor  The common ancestor is in the group  Example: Birds and Reptiles Ancestor was a bird like reptile 24

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 25

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 26

Cladogram for Transportation  Wheels are the most ancestral  Wings are the most derived 27

Construct a Cladogram 28

Gorilla  Four limbs  Fur  Lost tail 29

Tiger  Four limbs  Fur  Tail 30

Lizard  Four limbs  Tail 31

Fish  Tail 32

Chimpanzee  Four limbs  Fur  Lost tail 33

Clad With 4 Limbs 34

Clad With Fur 35

Clad With No Tail 36

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 37

38 GorillaChimpanzee Tiger Lizard Fish Four Limbs Fur Tail Lost

Gorilla Tail?  How do we know the gorilla lost its tail? 39

Gorilla’s Vestigial Tail 40 Gorilla Human

The End.