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A Mini-Lesson

 

ISLAND BIOGEOGRAPHY
AND
EVOLUTION:
Solving a Phylogenetic Puzzle
With Molecular Geneics

R.P. Filson

EVOLUTION

Speciation

 CLICK HERE for a quick but impressive and effective
Interactive Demonstration of How Speciation Can Occur

 SYNOPSIS

Using real data, students develop likely phylogenies for seven related populations of lizards living on the Canary Islands (off the West coast of Africa). Three phylogenetic charts will be constructed, each using different forms of data: geography, geology, morphology, and molecular genetics (DNA comparisons). Serves as an excellent example of MILE: Multiple Independent Line of Evidence, showing at least some degree of similarity of patterns and therefore mutual confirmation of the phylogeny.

 CONCEPTS

1. Speciation involves genetic differentiation, ecological differentiation (niche separation) and reproductive isolation.

2. Scientists use a variety of criteria to compare explanations and select the better ones.

 MATERIALS

Handouts
Scissors and tape
An atlas would be a desirable option

 STUDENT HANDOUTS
 

 (see end of lesson for the formatted handouts).

All information, preparation, and handouts can be found on the
University of California at Berkeley Museum of Paleontology web site in their "Learning From the Fossil Record" section.

This will take you out of the ENSIweb site, so to get back here, click on "Back", or select ENSIweb from the "Go" in your browser menu.

 TEACHING STRATEGY

 EXTENSIONS & VARIATIONS

 SPECIAL NOTE: Click here to explore many of the different lines of evidence pointing to speciation and macroevolution.

MACROEVOLUTION DIAGRAM: See the Macroevolution Diagram and a page of directions for using that diagram on an overhead projector. This nicely shows how accumulated speciations can eventually form all the groups and subgroups of organisms. It also shows how classification is related to evolution. A very nice colorful version of this can be found on page 32 of that most useful resource: Teaching About Evolution and the Nature of Science, by the National Academy of Sciences (1998) (see our Resources section). A particularly interesting alternative diagram is the one Darwin included in The Origin of Species (chapter IV), the only diagram in that book! His discussion there of that diagram should be required reading for any biology teacher. Darwin's Tree makes a great overhead transparency for discussing his concept of evolution by natural selection, as well as how classification reflects that evolution.

 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: R.P. Filson, Edison High School, Stockton, CA

 


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