Bell Work List 2 sister groups in the

Bell Work • List 2 sister groups in the phylogeny.

Intro to Biology – Lecture 60 Cladograms

Cladogram • A diagram used to show relations among organisms.

What Does a Cladogram Look Like? • Uses lines that branch off in different directions ending at groups of organisms. • Many shapes but all have lines that branch off from other lines. • The lines can be traced back to where they branch off.

Branching Off Points • Branching off points represent a hypothetical ancestor which would have the combined traits of the lines above it. • This hypothetical ancestor might then provide clues about what to look for in an actual evolutionary ancestor.

How are Cladograms Made • Originally – made by observing morphological characteristics • Today – made by sequencing DNA and RNA

Minor Differences Between Cladograms and Phylogeny Cladogram • The length of branches represents the time for a species to change. • Relates organisms based on comparisons of the similarities/dissimilarities of their anatomies. • Measures degrees of similarity. • Concerned with who appears most similar to whom at one point in time. • Branch length has no relevance to time. • Attempts to trace evolutionary relationships directly by analyzing gene sequences. • Traces the sharing of derived characters. • Does not show ancestors are related to descendants or how much they have changed

Cladogram vs Phylogeny

Cladogram and Phylogeny • Often the two methods give the same tree, but sometimes they differ because of the minor differences in the way they are formed.

Cladogram and Phylogeny • For the purpose of this class, we will assume that the two are the same.

The Same

More of the Same

Example Cladogram

Create a Cladogram Characteristic Cells /Organism Slug Catfish Frog Tiger Human Backbone Legs Hair Opposable Thumbs

Practice - Cladogram cells Worm Spider Ant Fly legs 6 legs wings

Cladogram Practice Characters Vertebrae Two pairs of limbs Mammary glands Placenta Shark Bullfrog Kangaroo Human X X X X X

Cladogram Practice TRAITS Dorsal Nerve Cord Notochord Paired Appendages Vertebral column Kangaroo Monkey Bullfrog Human Snapping Turtle Tuna X X X X X X X Paired legs Amnion (Amniotic sac) Mammary Glands Placenta Canine teeth short Foramen magnum fwd X

Cladogram Practice Organism Vascular Tissue Flowers Seeds Mosses 0 0 0 Pine Trees 1 0 1 Flowering Plants 1 1 1 Ferns 1 0 0

Cladogram Practice ORGANISM DERIVED CHARACTERISTIC BACKBONE LEGS HAIR EARTHWORM ABSENT TROUT PRESENT ABSENT LIZARD PRESENT ABSENT HUMAN PRESENT

Pop Quiz

Pop Quiz – Fill in the Chart and the Cladogram Correctly hair Human Snake Monkey Mouse legs thumbs eyes