Essential knowledge 1.B.1: Organisms share many conserved core processes and features that evolved and are widely distributed among organisms today.

Structural and functional evidence supports the relatedness of all domains Can you think of any evidences that support the claim that all living things are related?

Evidence #1: Major features of the genetic code are shared by all modern living systems

Evidence #2 DNA and RNA are carriers of genetic information through transcription, translation and replication.

Evidence #3: Metabolic pathways are conserved across all currently recognized domains. http://genome.cshlp.org/content/13/3/422.long Scientific study to support the claim. Have student read the article and discuss in class. Abstract is on the following slide http://www.salk.edu/news/pressrelease_details.php?press_id=484 A second article supporting evidence #3

The Phylogenetic Extent of Metabolic Enzymes and Pathways José Manuel Peregrin-Alvarez, Sophia Tsoka, and Christos A. Ouzounis1 Computational Genomics Group, The European Bioinformatics Institute, EMBL Cambridge Outstation, Cambridge CB10 1SD, UK Abstract The evolution of metabolic enzymes and pathways has been a subject of intense study for more than half a century. Yet, so far, previous studies have focused on a small number of enzyme families or biochemical pathways. Here, we examine the phylogenetic distribution of the full-known metabolic complement of Escherichia coli, using sequence comparison against taxa-specific databases. Half of the metabolic enzymes have homologs in all domains of life, representing families involved in some of the most fundamental cellular processes. We thus show for the first time and in a comprehensive way that metabolism is conserved at the enzyme level. In addition, our analysis suggests that despite the sequence conservation and the extensive phylogenetic distribution of metabolic enzymes, their groupings into biochemical pathways are much more variable than previously thought.

Structural evidence supports the relatedness of all eukaryotes. How similar are you to a banana? Answer: Very closely related

Example 1: Cytoskeleton (a network of structural proteins that facilitate cell movement, morphological integrity and organelle transport)

Example 2: Membrane-bound organelles (mitochondria and/or chloroplasts)

Example 3: Linear chromosomes

Example 4: Endomembrane systems, including the nuclear envelope

Essential knowledge 1.B.2: Phylogenetic trees and cladograms are graphical representations (models) of evolutionary history that can be tested.

Cladograms

Look at the cladogram at the right Look at the cladogram at the right. What conclusions can be drawn about the relationship between humans and chimps? Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_05

How to read a Cladogram This diagram shows a relationship between 4 relatives. These relatives share a common ancestor at the root of the tree. Note that this diagram is also a timeline. The older organism is at the bottom of the tree. The four descendents at the top of the tree are DIFFERENT species. This is called SPECIATION. Stress that cladograms not only serve as a pictorial representation of lineage, but also as a snapshot in time. Be sure to introduce the term SPECIATION. The four descendents are DIFFERENT species. Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_05

The event that causes the speciation is shown as the fork of the “V”. Branches on the tree represent SPECIATION, the formation of a new species. The event that causes the speciation is shown as the fork of the “V”. Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_05

Species B and C each have characteristics that are unique only to them. But they also share some part of their history with species A. This shared history is the common ancestor. Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_05

Write a sentence that summarizes the relationship between A and B Write a sentence that summarizes the relationship between A and B. What is the only thing A and B have in common? Be sure to have students justify their answer to the question. Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_05

A CLADE is a group of organisms that come from a common ancestor. If you cut a branch of the tree, you could remove all the organisms that make up a CLADE. Students should be able to decide if a group of organisms form a clade. Image courtesy of http://evolution.berkeley.edu/evolibrary/article/0_0_0/evo_06

3 Groupings

Bozeman - Cladograms http://www.youtube.com/watch?v=ouZ9zEkxG Wg