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Students investigate the evolution of taste receptors by using protein sequence data to generate a phylogenetic tree of sweet, umami and bitter taste receptors from six animal species. In a second, more advanced activity, the evolution of bitter taste receptors by gene duplication is studied using DNA sequence data. The unusual case of the giant panda, which has lost the ability to taste meaty flavours, is also introduced.
DNA to Darwin
Be sure to test the free software used in this lab before attempting it with students. Some users have reported trouble, while others have had none. Also, be sure to fully test the activity yourself before using it. Some students may find the directions confusing. However, with a few clarifications, these activities are worthwhile.
Correspondence to the Next Generation Science Standards is indicated in parentheses after each relevant concept. See our conceptual framework for details.
- Biological evolution accounts for diversity over long periods of time.
- Present-day species evolved from earlier species; the relatedness of organisms is the result of common ancestry.
- The patterns of life’s diversity through time provide evidence of evolution.
- There is a fit between organisms and their environments, though not always a perfect fit.
- An organism's features reflect its evolutionary history.
- Features sometimes acquire new functions through natural selection.
- Evolution results from natural selection acting upon genetic variation within a population.
- Traits that confer an advantage may persist in the population and are called adaptations.
- Scientists use multiple lines of evidence (including morphological, developmental, and molecular evidence) to infer the relatedness of taxa.
- Evolutionary trees (i.e., phylogenies or cladograms) portray hypotheses about evolutionary relationships.
- Evolutionary trees can be used to make inferences and predictions.