Evolutionary Biologist OnlineHS > Biology A

Overview  View this PowerPoint and record the items in your journal.  Read the Evolutionary Biologist Interview & answer the questions in your journal.  Read the article “Modern Life: Evidence for Evolutionary Change” & answer the questions in your journal.

Evolutionary Biologists  Evolutionary biologists are scientists who study how living organisms change physically over time.

Interview with an Evolutionary Biologist  Use the course link to the PDF & Read the Evolutionary Biologist interview.  Take notes in your journal  How would you explain the job of this scientist?

Study the color coded images below

In Your Journal, Explain Explain the similarities that you found between the limbs of: Human Cat Bat Porpoise Horse

Basic Terminology Ancestral TraitA trait inherited from an ancestor. Conserved TraitAn ancestral trait shared between most or all of the ancestor’s descendants. Derived TraitA trait that differs from its ancestral form. Convergent EvolutionWhen independently evolved features subjected to similar selective pressures become superficially similar. An example is the wings of birds and insects. Evolutionary ReversalWhen a character reverts from a derived state back to an ancestral state. Homologous TraitAny trait (nucleic acid, behavior or morphology) shared by two or more species descended from a common ancestor. For example, an ancestral trait shared by two species is homologous between the two. HomoplasiesAlso known as homoplastic traits, they are traits similar for some reason other than inheritance from a common ancestor. For example, the wings of birds and insects are homoplasies. Analogous TraitsA homoplastic trait that has arisen due to convergent evolution or evolutionary reversal. For example, the wings of birds and insects are analogous traits. Vestigial StructuresStructures that are no longer of adaptive value and therefore not maintained by selection. For example, the forearms of Tyrannosaurus rex.

Homologous vs. Analogous Use the picture to describe & explain in your journal the difference between Homologous & Analogous structures.

Read the Essay & Answer  Use the link in the course to the PDF & read “Modern Life: Evidence for Evolutionary Change”  Answer the following questions in your journal: By comparing the anatomy of different organisms, scientists have noted similarities in structure. Patterns of similar characteristics may suggest what? Describe the word vestige. How are goose bumps vestigial in humans? How do birds use these muscles (goose bumps)? Can DNA be transferred from one organism to another and be functional? How does this [similar DNA] show relatedness between organisms?

Vestigial Structures (from top to bottom left to right)  Muscles to move ears  Body Hair  Appendix  Nictitating Membrane  Third molar/pointed canine  Tailbone

Why are these structure vestigial? Write a brief explanation for each one: Muscles to move ears Body Hair Appendix Nictitating Membrane Third molar/pointed canine Tailbone  Find more at:

Why are these hind limbs considered vestigial? Why are these structures vestigial?

Final check:  View this PowerPoint and record the items in your journal.  Read the Evolutionary Biologist Interview & answer the questions in your journal.  Read the article “Modern Life: Evidence for Evolutionary Change” & answer the questions in your journal.