Classifying Organisms

Tree of Life Organizes all living things into related relationships through Related form Related function Related evolution Always changing and being modified with new organisms

Organization of organisms Domains Kingdom Phylum Class Order Family Genus Species D - K – P – C – O – F – G – S (Pneumonic device)

3 Domain System Bacteria Archaea Eukarya ** Primarily separated by composition of cell wall**

3 Domains Archaea Bacteria Unicellular - unicellular prokaryotic (no nucleus) No peptidoglycan in cell wall Many live in environments that have no oxygen Bacteria - unicellular - prokaryotic (no nucleus) - peptidoglycan in cell wall - Live in diverse environments

3 Domains Open books to 459, fill 3 characteristics for each Kingdom Eukarya Consists of 4 Kingdoms Protista Plantae Fungi Animalia

Organization using Cladograms Shows evolutionary relationships Contains current organisms and common ancestors Shows derived traits between organisms Identifies the out group = most basic organism (least amount of changes)

Cladogram Example Current Organism Out group Common Ancestor Derived Trait

Classification and Evolution

Similarities between organisms List three ways we classify organisms Similar form Similar function Similar evolutionary history Sometimes body structures can provide missing evidence for common ancestors

Specific ways we classify Homologous Body Structures Vestigial Organs Analogous Body Structures DNA and RNA sequences (molecular clocks)

Homologous Body Structures – body parts that appear different but arose from similar evolutionary histories

Why use homologous body structures to classify? Shows a change over time from a common ancestor Shows how the organisms have adapted to live in its environment A change in structure is not a choice yet rather a chance happening that helped the organism in its environment

Unimportant Homologous Body Structures Although they have nearly no function, they do show a link to a common ancestor Vestigial organ – traces of homologous organs in other species

Vestigial Organs Describe a vestigial organ/part in your body.

Analogous Body Structures Look at the following pictures. Describe 3 similar characteristics shared between the two. Shark Dolphin

breaths air through lungs Dolphin skeleton bone breaths air through lungs horizontal fin nurses young skin has hair Shark skeleton cartilage oxygen from gills vertical tail Analogous Body Structure – body parts that appear similar but arise from separate evolutionary histories

Using body structures to classify Although similar, a shark and dolphin not closely related (do not share a recent common ancestor) Similar does not always equal same Convergent Evolution – organisms evolve similar structures independently, often due to similar environments

DNA and RNA sequences (molecular clocks) Uses differences in DNA/RNA sequences to show evolutionary history More closely related species have more similar DNA/RNA sequences Neutral Mutations accumulate within specific area at the same rate

DNA and RNA sequences (molecular clocks) Tracing neutral mutations backwards through time can help estimate time since the most recent common ancestor A B C Leads to