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MOLECULAR SEQUENCES &
PRIMATE EVOLUTION

Amino Acid Differences in Beta Hemoglobins in Primates

 

Craig Nelson & Martin Nickels

Edited by Larry Flammer

EVOLUTION

Human Evolution Patterns

 SYNOPSIS

Students compare differences in amino acids in the beta hemoglobin from representative primates, complete a matrix of those differences, and from these data, construct and interpret cladograms as they reflect relationships and timing of divergence.

 PRINCIPAL CONCEPT

Modern apes and humans evolved from a common ancestor.

 ASSOCIATED CONCEPTS

1. The groups-within-groups hierarchical pattern of Linnaean classification is a result of both extinction and branching from common descent.

2. The evidence that humans have evolved from non-humans is as strong as or stronger than that for evolution within most other groups.

3. Molecular comparisons of different groups generally reveal degrees and patterns of relationship consistent with that revealed by other kinds of comparisons (anatomy, fossils, embryology, cytology, etc.)

4. Cladistics is helpful for showing common ancestry and sequence of evolution between taxa.

ASSESSABLE OBJECTIVES

   Students will....

1. Given sample data (amino acid differences in proteins from individuals in different groups), students will build a matrix of differences.

2. From the matrix of differences, students will construct a reasonably parsimonious cladogram of the groups, and correctly answer questions regarding inferred evolutionary relationships based on the cladistic analysis.

3. Students will cite how the results of this lesson match the results of other lessons showing patterns of primate relationships based on different criteria (e.g., hominoid skull and chromosome comparisons).

4. Students will explain how and why biological classification is different from the categorization of non-biological objects.

 MATERIALS
   For PDF access page to download pdf files, click here.

- Background and Teacher Preparation (4 pages pdf)
- Student Procedures (5 pages pdf)
- Data Sheet (pdf)
- Worksheets (2 pages pdf)

Cladogram demos with Geomag™ magnets (Clado. A and B)

Overheads of Worksheet diagrams (for class data collection and discussion)

 TIME

One to two 45-55 minute periods
STUDENT HANDOUTS See "Materials" list
- Student Procedures
- Data Sheet (can be placed in plastic sleeve, or laminated)
- Worksheets

 TEACHING STRATEGY
   For PDF access page to download pdf files, click here.

This lesson is most powerfully effective when used in conjunction with other lessons which show the same pattern of evolutionary relationships in primates, based on different kinds of evidence (e.g., hominid skull and chromosome comparisons). This congruence across different sets of biological data presents compelling evidence of evolution, especially in the pedagogically attractive category of human evolution.

This congruence also distinguishes biological classification from the categorization of non-biological objects, a fact which should not be ignored. See Nuts & Bolts: Is Classification Arbitrary, or Not? on this site.

This lesson can also simply be used as a stand-alone lesson to illustrate an application of molecular analysis to inferring biological relationships, either in a molecular biology unit, or an evolution unit.

Detailed preparation and discussion points to be achieved in the several sections can be found in pdf format by clicking on the pdf access link on the left.

CLADO-DEMO: Students sometimes have difficulty seeing how cladogram B is the same, biologically, as cladogram A. The use of a linear construction toy can help to show how each node (branching point) can be rotated horizontally to modify the arrangement, yet still retain the same connectedness. For example, see the display photos of Geomag™ magnets (from box of 20 parts for $10), a Swiss-made toy available at toy stores. You could also try the larger Zoob™ pieces, 55 parts for $15. In the Geomag demo, note that the magnets forming a direct line to humans (nodes 4, 5, and 6) have been darkened. Magnets come in different colors (one color per box). You could use them on your overhead, or on your magnetic whiteboard.

PROCEDURES

Student Procedures are detailed in the 5-page pdf format, Expected responses to questions are found in the Background and Teacher Preparation packet.

ASSESSMENT

Prepare and administer a test which includes the assessable objectives listed above. Some of the discussion questions found in the procedures could also be used.

EXTENSIONS

& VARIATIONS   

Deeper mastery of the concepts and more confirmation of the strength of the evidence for human evolution (as well as for evolution generally) can be achieved by searching out and comparing other molecules. See the Tutorial on this site: "Tutorial: Investigating Evolutionary Questions Using Online Molecular Databases."
This tutorial will take the student step-by-step through the process of selecting a protein molecule to compare, the organisms to use for amino acid sequencing, how to run an online comparison application, and how to build a comparison matrix from those data: It utilizes the ExPASY, Swiss-Prot, and Lalign online molecular analysis tools, and explains how to use them.

In addition, don't overlook the lessons on this site that provide experience with comparing hominid skulls, hominid chromosomes, and human vs chimp chromosomes. The congruence of the results from these lessons and the molecular sequence lesson is a powerful and compelling example of how scientific understanding is strengthened by multiple independent lines of evidence (MILEs).

Even more appropriate would be to follow one of the chromosome comparison lessons above with our Chromosome Fusion lesson, where specific DNA segments are analyzed to show clear evidence of fusion.

 

RESOURCES

Useful article in Molecular Clues to Evolution briefly explains how pseudogenes in beta hemoglobin, reveal the evolutionary history of the hemoglobin family, with useful diagrams (page 27 in article). Vertebrate phylogeny based on alpha hemoglobin shown on page 29.

R.P. Hershberger. 2000. What I could teach Darwin using "Darwin 2000," an interactive website for student research into the evolution of genes and proteins. Tested Studies for Laboratory Teaching 21:4-32 Association for Biology Laboratory Education.

R.Moss.1999. The molecular evidence for evolution. Journal of College Science Teaching 29:111-113. Also features student use of public, on-line databases.

S.D. Brewer. 1997. Constructing Student Problems in Phylogenetic Tree Construction.Paper presented at the Annual Meeting of the American Educational Research Association (Chicago, IL, March 24-28, 1997).EDRS DOCUMENT LINK: non operative.

Genbank, National Center for Biotechnology Information: <http://www.ncbi.nlm.nih.gov>

See also the lessons, tutorials and advanced resources directly available through the "Biology Workbench" homepage:<http://peptide.ncsa.uiuc.edu/>

 ATTRIBUTION

Some of the ideas in this lesson may have been adapted from earlier, unacknowledged sources without our knowledge. If the reader believes this to be the case, please let us know, and appropriate corrections will be made. Thanks.

1. Original Source: Craig Nelson & Martin Nickels

2. Edited / Revised for website by L. Flammer 11/17/01

3. Major Revision by L. Flammer 5/23/2005, based on the many suggestions by teachers and students. Special gratitude is extended to teacher Julie McIntyre of Ontario, Canada, and teacher Amanda Palla and her Advanced Biology students at Urbana HS in Urbana, IL.

 

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