Introduction | Overview | Teacher Resources

About This Lab

About This Lab | Key Concepts | Classroom Use | Tips | Curriculum

This virtual lab explores phenotypic, or trait, diversity in several related stickleback populations. It emphasizes quantitative measurement of phenotypic diversity and encourages thinking about the role of natural selection and genetic mechanisms of evolution.

This lab makes an excellent companion to an evolution unit. Because the trait under study is fish pelvic morphology, the lab can also be used for vertebrate form and function lessons. In an ecology unit, it can be used to illustrate predator-prey relationships and environmental selection pressures. The focus on graphing, data analysis, and statistical significance makes the lab a good fit for addressing "science as a process" or "nature of science" aspects of the curriculum.

Students would benefit from watching the 15-minute HHMI film The Making of the Fittest: Evolving Switches, Evolving Bodies, available at http://www.hhmi.org/biointeractive/making-fittest-evolving-switches-evolving-bodies, prior to doing the experiments in this virtual lab.

Lab Description

The lab has two tutorials in which students practice how to score stickleback pelvic structures in both fixed fish and fossil fish. Once students have gained confidence in the technique, they can proceed to the experiments.

The lab was designed to be modular; students may complete one, two, or all three experiments, each in its entirety or just portions of it. Each experiment includes a data-gathering portion, a graphing section, a statistical analysis section, and a quiz. The lab also contains an overall quiz that tests knowledge acquired by working through all sections of the lab.

• Experiment 1: Analyze Fish from Lakes. Students stain fish collected from two lakes and score each specimen as having complete, reduced, or absent pelvic structures. The data are graphed and analyzed with the option of doing a chi-square analysis. In the quiz, students are asked to make predictions about selective pressures in the lakes.
• Experiment 2: Analyze Fossil Fish. Students score fossil specimens collected from six different strata of a now-dry Nevada lakebed. Data analysis includes rate-of-change calculations. The quiz tests students' understanding of how fossil analysis provides insights into evolution over time.
• Experiment 3: Pelvic Asymmetry. Students score stickleback pelvic morphology, specifically noting asymmetry in pelvic reduction, and measure statistical significance using chi-square analysis. This experiment illustrates how detailed analysis of morphology can provide insights into genetic mechanisms of evolution.

Using the Lab in the Classroom

The entire lab takes approximately 2.5 to 3.5 hours to complete, depending on the student. Educators have a great deal of flexibility as to which portions of the lab they would like their students to do and whether the students should do the assigned sections at home or in class, working individually or in groups. Based on students' evaluation data, students enjoy working in pairs or small groups and they complete the lab more quickly when doing so.

For some suggestions on how to implement this lab in the classroom, click here. For correlations to various curricula, click here.

Having Students Save Their Progress

As a student proceeds through different module, the lab keeps track of progress, which can be reviewed anytime by going to the Progress tab. If the student exits the lab at any stage and returns to it later, the student will have the option to resume the lab where he or she left off as long as the student uses the same computer and no one used that computer for the virtual lab in the meantime.

Note that some schools clear all history and cookies from computers at the end of the day. If that happens all progress will be erased. Students should read the information under the "Save/Resume" tab for instructions on how to manually save their progress.