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Copyright © 2002-2003 D.J. Eernisse. All Rights Reserved.

Phylogeny Part 1 (Review): CLADOGRAM CONCEPTS AND TERMS:
Cladogram Terminology: Start with some basic definitions of terms such as node and branch.
Sister Taxa: Learn what a sister taxon is and why recognizing them will help you with all of the following steps.
Cladogram Styles: Examples of the same cladogram drawn in different styles and orientation.
Rotate at a Node: Are the two cladograms identical, merely rotated at nodes, or are they different topologies?
Polytomies: Are they "hard" or "soft" and how do they relate to strict consensus estimates?

Welcome to the online Cladogram Exercise 2 Web site. This online assignment will introduce you to how phylogeneticists come up with their best supported cladograms and how they use them to interpret patterns and processes of evolution. The links immediately above are provided for your review and will bring you back to Cladogram Exercise Part 1. Use the browser's "Back" button to return here. Your feedback is valuable and encouraged.

Read the instructions below and then click on the Cladograms Summarize Evolution link to start the Cladogram 2 Exercise.

2. Cladograms Summarize Evolution: A cladogram can be used as a roadmap to the evolutionary history of a group.

How to turn in Part 2 of this Web assignment.

CQ1 (1 pt): Look at this "bubble diagram" tree and use it to formulate a short conjecture (about 25 words or less) about what sort of ancestor a bird might have evolved from. Please do this before you proceed further. If you are really a glutton for punishment, attempt to draw a cladogram version of this figure.

CQ2 (1 pt.): Now, repeat what I asked you to do above in CQ1. Hypothesize what sort of ancestor gave rise to birds, only this time use the cladogram views. It might be helpful to start at the node where birds are on the second cladogram, then move down in the cladogram to the next node down, to include more general traits for more inclusive clades that also include birds, and keep moving down until you are at the bottom node of the first cladogram. If you forget what a clade is, remember the "snip rule."

CQ3 (2 pts.): Briefly contrast the descriptions derived from the "bubble diagram" tree (CQ1) and the amniote/dinosaur cladograms (CQ2). What can you conclude about these alternative approaches with respect to making statements about the evolution of traits?

CQ4 (2 pts.): Extend this reasoning to complete the following sentence. The taxon _____________ is the sister taxon of theropods, and these are daughter taxa nested within the higher taxon ____________. One trait that unites members of this higher taxon is ___________________.

CQ5 (2 pts.): Find the node (blue dot) corresponding to the last shared common ancestor of birds in the OLogy cladogram, and complete the following sentence. The sister taxon of birds is _____________________ and within birds, the living but flightless bird, Eudromia elegans, is sister taxon of a clade of extinct birds, __________ and Presbyornis pervetus (according to this cladogram hypothesis). Extra challenge: If it is related to modern ducks, could Presbyornis pervetus quack, according its species card on this web page (click on its name, and then the yellow arrow)?

CQ6 (2 pts.): Consult this Archaeopteryx web page. Name some derived (new) features that modern birds share that are lacking in the ancient bird, Archaeopteryx (and also lacking in other dinosaurs). Next, name some derived features that Archaeopteryx shares in common with those other dinosaurs known as birds.

1. Use a simple numbered list numbers corresponding to the cladogram questions (CQ) as numbered (1-6) above, starting with CQ1 here.
2. Unlike Part 1, these answers are fill-in-the-blank or short answer.
3. Submit your answers by email either directly in your email text or as an attachment in text, MS Word, or PDF format.
4. Include your name or your answers cannot be graded.
5. The deadline for receiving your email must be sooner than the date on the course schedule! You will get a confirmation that your answers were received within 48 hours!  Contact Dr. Pelaez (npelaez@fullerton.edu) if you do not get your confirmation.
6. Feel free to work together with your classmates but every student must email separately.
7. This assignment is worth 10 points total (1 or 2 points per question, as indicated before each question above).
8. Send your answers to Dr. Pelaez (npelaez@fullerton.edu), but E-mail Prof. Eernisse (deernisse@fullerton.edu) if you find problems with these instructions (include your name and email address).
   
   

Feedback on particular questions that confused you are welcome!
Email feedback to deernisse@fullerton.edu

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