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Teachable Unit: Utilization of evidence to construct the tree of life. Group (Fabulous) 5 Laura Hake, Jenny Frederick, Carl Hashimoto, Kirsten Fertuck , Bill Rando , Serena Moseman Facilitators: Steve Chordas III, Justin Hines. Teaching Unit Goals and Outcomes. Context.
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Teachable Unit: Utilization of evidence to construct the tree of life Group (Fabulous) 5 Laura Hake, Jenny Frederick, Carl Hashimoto, Kirsten Fertuck, Bill Rando, Serena Moseman Facilitators: Steve Chordas III, Justin Hines
Context • Introductory general biology course for majors or non-majors • Evolution unit (mid-semester) • Topics taught prior to this: -genome composition -definitions of species, phylogenies -reading phylogenetic trees -the value of the tree of life - using trees to evaluate evolutionary relationships Broader goal: to illustrate how knowledge is constructed.
Prior Assignment: Tree building with aliens (in Mastering Biology- Pearson) Check your homework: How many aliens did you place correctly on the tree? 5 4 3 2 1 or 0
Choose the statement that is true about how scientists use evidence to create the tree of life. (A) The phylogenetic tree was recently updated with new evidence and now it is complete. (B) There are multiple trees of life that are strongly supported by evidence. (C) The purpose of the tree of life is to show how organisms are related to humans. (D) The increased number of recent revisions to the tree of life suggest that it is no longer a useful tool. (E) None of the above.
Tid bit #1: Morphology as evidence Learning Goal • Students will understand how morphology is used as evidence to build a phylogenetic tree. Learning outcome: • Students will use morphological traits to evaluate similarities and differences between animals.
Cow Deer Pig Hippo Whale camel
whale Using morphology… 1. Which one animal appears to be most distantly related to the others? 2. Which two animals appear to be most closely related to one another? Pig Hippo Deer Record your answers and the evidence that supports your choices. Cow Camel
With more data, we can be more certain about these relationships. What other kinds of evidence could be used?
QUICK CLICK: Which animal is most closely related to the deer? (A) Cow (B) Hippo (C) Pig (D) Camel (E) All are equally related One (of several) traits supporting relationship A
Which is true about the use of morphology in tree-building? • Morphological evidence is always weaker than molecular evidence. • Morphological evidence has no value for determining evolutionary relationships. • Morphological traits are always visible. • It is one of many pieces of evidence used to construct trees. • Morphology cannot be used for bacteria.
Evidence That Whales and Hippos Form a Monophyletic Group Tid bit #2: Sequence data as evidence Data on the presence and absence of SINE genes support the close relationship between whales and hippos. 1 = gene present 0 = gene absent ? = still undetermined Whales and hippos share four unique SINE genes (4, 5, 6, and 7) …and is later confirmed by fossil evidence! 15