A Lesson on Eye Evolution Biology Lab Report
During this lab exercise you will learn about how eyes evolved and why the eyes of different animals are similar in some ways but not others. You will learn about the occurrence of homologous structure and how homologies illustrate both the unity and diversity of life.
If you are not familiar with the terms homology and homologous structures, you will find it helpful to read through the information posted Understanding Evolution web site at the following link: http://evolution.berkeley.edu/evolibrary/article/lines_04
II. The Lab Exercise
To do this exercise, you will need to visit the website indicated below, and as you navigate through the various screens, you will need to provide answers to questions pertaining to specific sections of the site.
Web site: http://evolution.berkeley.edu/evolibrary/article/0_0_0/eyes_02
III. Eye Evolution Questions (Submit your completed answers in lab on 02/20)
A. Diverse Eyes (http://evolution.berkeley.edu/evolibrary/article/0_0_0/eyes_02)
1. What function do simple light gathering pigment cells serve for organisms that currently have them?
2. What would be the advantage to a turbellarian worm to be able to sense light?
Side Trip: How Your Eye Works
3. What features of human eyes do we share with more primitive vertebrates such as fish? Why does it cause problems for humans?
B. Introducing the Visionaries Finding Homologies
Read through the sections Introducing the Visionaries and Finding Homologies:
4. Click on each organism to view information about their eyes. Fill in the table on the next page as you go. Leave the gene information until later.
Evolution of Eyes
Squid Flat worms Mouse Flies Sharks
How do they use their eyes?
Composition of the eye
Gene involved in eye formation
5. Based on the information from your table, take the quiz. Which eyes are homologous? (http://evolution.berkeley.edu/evolibrary/article/0_0_0/eyes_05 )
6. Which eyes are analogous?
C. Mapping The Eyes On The Tree (http://evolution.berkeley.edu/evolibrary/article/1_0_0/eyes_06)
7. What do genes do?
8. How do genes control other genes to build complex structures like eyes?
9. What is the name of the control gene involved in eye development? What kind of gene is it?
D. Surprisingly Similar (http://evolution.berkeley.edu/evolibrary/article/1_0_0/eyes_08)
10. How similar is the DNA sequence of the eye control genes (HOX genes) in flies and mice?
11. How similar are the proteins made by the eye control gene in flies and mice?
12.What is the relationship between the eyeless gene in flies, the pax6 gene in mice and the Aniridia gene in humans?
13. What do these genes tell the organism to do?
E. Homologous Genes
Go back to your table. Add information about the genes to your table.
14. Are the genes for the formation of eyes homologous or analogous? What is the evidence that supports your answer?
F. Evolving Two Eyes With One Gene & Homologies at Different Levels
15. Read through the material. Write a paragraph explaining how eye development in these animals can contain both homologous and analogous components.
Side Trip: Evolving Complexity
16. Identify how natural selection could favor steps in the evolution of a complex structure, such as the eye.
VIII. Final Instructions
You should submit (=email) this lab assignment as a Word document. Your file must be named in the following manner: your last name and the number of the lab assignment. For example: Smith Lab 7.docx.