Exploring Evolution

Evolution is a scientific theory that explains not only how organisms change over time, but also the diversity of species. In order to support this theory, scientists have had to gather evidence from a number of sources. In this web lab, you will act as a scientist looking for evidence to support a theory. Follow the instructions in the web lab and record your observations on the investigation sheet provided.

Problem: What are the whale's closest relatives?

Hypotheses:

Hypothesis 1 Whales evolved from a land animal.

Hypothesis 2 Whales evolved from the mesonychids, and extinct group of perissodactyls.

Hypothesis 3  Whales evolved from group of artiodactyls.

Go to  Exploring Evolution

Evidence:

Evidence from Genetics:

DNA samples obtained from closely related individuals have more of the same DNA sequences. DNA from more closely related species are more likely to have more similarities in their DNA sequences. In this activity you will compare sequences of DNA from different species to infer their phylogeny.

Evidence from Fossils:

Paleontology provides a great deal of evidence for the theory of evolution. Fossilized remains provide scientists with physical evidence of past life. This section of the investigation will have you examining the fossil evidence to help determine the whale's closest relatives.

Evidence from Skeletons:

In this section of the investigation you will be comparing the physical anatomy of different species and identifying the homologous features of each. The whale skeleton has several vestigial features that will provide more evidence for the evolutionary path of whales.

Conclusion

You should now be able to support one of the original three hypotheses with the evidence that you have gathered from this investigation. It is generally accepted that modern cetaceans descended from a group of animals that lived on land and may have fed while wading in shallow streams. Click on the link below to view the ancient ancestor of the modern whale family.

Pakicetidae

Additional Activities

VISIT THE WHALE EVOLUTION KIOSK. This is a new, very clever interactive online experience for your students, created by Lara Sox-Harris at San Jose State University, who has kindly consented to this link. When you click on the title (Whale Evolution Kiosk) above, it will take you into a self-guided tutorial on the necessary elements of whale anatomy, fossils, DNA, and classification. These will all provide the mutually reinforcing evidence for whale evolution, all in delightful animations and interactions. Help your students with a guided tour of the kiosk, providing more focus, and a way for you to confirm that they probably did indeed visit the site, give them the Whale Evolution Kiosk Worksheet. This was developed and kindly shared with us by Gail Bromiley of DeBakey H.S. in Houston, TX. Gail also provides a key to facilitate your discussion of the site and worksheet.

Whale of a Change Video Resource Whale Evolution Data Table
 

Resources

Whale Origins
Exploring Evolution
Introduction to Cetacea
Evolution: Teachers' Guide