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Evolutionary Relationships
Evolutionary Relationships

Learning Objectives

At the end of this lab, students should know...

What are synapomorphies?

Synapomorphies are measurable or quantifiable physical features which can be used to distinguish and split groups of living organisms.

What are dendrograms?

A dendrogram is a tree diagram representing the evolutionary or cladistical relationships between groups of organisms.

What are two main types of dendrograms and how do they differ?

Cladograms and phylograms are the two main types of dendrograms. In a cladogram, the tips of the branches represent the species, and the branches simply show how they relate to one another. Nodes represent the last common ancestor. In a phylogram, the branches vary in length, with the length representing the amount of time that has passed since divergence from the last common ancestor.

What are the two main types of data used to create dendrograms?

Measurements or quantification of morphological and/or physical characteristics, or genetic data, may be used to construct dendrograms.

What is bioinformatics?

Bioinformatics is a combination of statistics, mathematical modeling, and computer science applied to biological information – like DNA or protein sequences.

List of Materials

Lab Prep

  1. Using BLAST to Test Evolutionary Hypotheses
    • Open the BLAST website on each computer that the students will be using. https://blast.ncbi.nlm.nih.gov/Blast.cgi
    • Navigate to the provided link to find the chicken, alligator, and zebra finch gene sequences. https://github.com/EvolutionGenes/Evolutionary-Relationships-Genes NOTE: These gene sequences will be used as the living relative DNA samples for the mystery fossil.
    • Click on the first sequence to familiarize yourself with it.
    • Return to the main page and click on the green “Clone or download” button.
    • Then, select 'Download ZIP'.
    • Save the files on the computer desktop for the students to access easily. Repeat steps 2 – 6 on each computer.
    • Print out a sufficient number of blank cladograms so that there is one per student. NOTE: It is recommended to also print spare cladograms.


JoVE Lab Lab: 5 Prep

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