"Fridays in the Lab" April 27th, 2007 Supported by a grant to Bryn Maw College by Howard Hughes Medical Institute.

 

Bones, Homology and Phylogeny

Start with Organizing/classifying organisms.

• Why did you organize them the way you did?
• See Paul Gobstein’s Organism Puzzle

Run EvoBeacker Simulation. Discuss events. Then pose the question…how do we know these relationships when no one was there to watch them…cannot be there because it takes too many lifetimes?

Genealogies: who are you most closely related to? Brother/sister, then parents then…?

Relationship between species: Vertebrates?

Look at vertebrates and tell me which ones share a common ancestor most recently…or in other words, which two are the most closely related

• Why? On what did you base your conclusion?

• Thus, similarity equals common ancestors. Why? Because decent
  w/ modification…you inherit your DNA from your parents
  
• Same with organisms. They look alike b/c they
  inherited DNA from common ancestors, from parent species.

• Geneology vs Phylogeny trees

So how do scientists represent evolutionary relationships?

• Vertebrate tree
  
  

Homology versus Similarity due to Convergence

• Homology = similarity due to common ancestry

• Homology home

• Convergent Similarities

  Other examples: fins, wings, others?

3 criteria

• Devo Bio (haeckel)

Students complete Homology Worksheet - bone activities

 

LUNCH

Students finish Homology Worksheet - bone activities

Demo Protein visualization:

 

Procedure for using Visualizing Protein Structure: Go to Entrez Protein - search: “per2 NP_073728”.

Amino Acid Phylogenetic Worksheet and Fish Gel review

Finish with web search of more fish info to first evolutionary fish tree.