Conceptual Change in the Fly Room:

1. Conceptual Change in the Fly Room: A Lesson for Undergraduate Biology Education M. Frances RoweEdgewood CollegeMadison, WisconsinUSAfrowe@edgewood.edu

2. Undergraduate Biology Education:A Challenge

3. Common Misconception Associated with Learning Genetics: • Students inability to relate meiosis to allele segregation • Students lack understanding of genetic terms (gene, allele, chromosome, gamete, trait) • Seeing dominant and frequent as the same • The perception that genetic ratios are determinate, not probabilistic • The relationship between genes and chromosomes, • The mechanisms for determining gender

4. Common Misconception Associated with Learning Evolution: • The belief that natural selection is both the production of variation and the selection of variations by environmental forces, rather than two separate processes affecting populations. • The belief that changes in environmental conditions direct changes in organisms’ phenotypes, “need” drives evolution. • A view of evolution as a change in an individual within its lifetime rather than evolutionary change seen as a changing proportion of individuals within a population over time. • The belief that acquired characteristics may be inherited. • The role of mutation in evolution

5. Thomas Hunt Morgan 1866- 1945

6. Bryn Mawr College Thomas Hunt Morgan 1891-1904 Nettie Stevens Edmund B. Wilson

7. Thomas Hunt Morgan 1904-1928 Schermerhorn Hall Columbia University

8. Thomas Hunt Morgan Naples1894-1895 • Embraced epigenesis as an explanatory theory for embryonic development • Introduced to Entwickungsmechanik, the German flavor of biology research, a mechanistic experimental approach • Converted from an observational research program to an experimental one, hypothesis testing Hans Driesch

9. Thomas Hunt Morgan Genetics Pre-1910 • He believed chromosomes were uniform, and questioned whether chromosomes changed during synapse • He felt that if many traits are on the same chromosome, it contradicted Mendel’s claim of independent assortment • Mendel’s theory of dominance and recessive variations could not account for the inheritance of sex in the observed one-to-one ratio • He did not believe continuous variation could be explained by Mendelian principles • There was no experimental evidence to support the existence of Mendel’s postulated “factors”

10. Thomas Hunt Morgan Evolution Pre-1910 • Darwin had provided no acceptable explanation for the origin of variation in organisms; • Believed that species were a human construction; • Morgan believed natural selection could only sort out the negative, not preserve the positive; • He did not believe natural selection could act on small adaptations to improve the function of particular organs, like the eye; • Darwin’s work was not supported by experiment; • Morgan questioned the role of chance in the process of natural selection

11. The Fly Room

12. The Fly Room Calvin Bridges Hermann Muller Alfred Sturtevant

13. The Fly Room

14. Fly Room • Genes are located on Chromosomes • The allele determining red or white eyes is located on the X chromosome

15. Fly Room • Linked genes tend to be inherited together because they are located on the same chromosome • Crossing over shuffles genes producing genetic recombinants

17. Fly Room • Recombination frequencies reflect the distance between genes on a chromosome • Recombinant data can be used to construct chromosome maps: an ordered list of the genes along a particular chromosome

18. Thomas Hunt Morgan 1910- 1930 Nettie Stevens Theodosius Dobzhansky Edmund B. Wilson

19. Thomas Hunt Morgan Genetics Post-1910 • Mendel’s factors must reside on chromosomes • Each factor resides on a particular chromosome • The eye color trait is positioned on the X chromosome • The red eye color variation is dominant to the white variation. Chromosomal Theory of Heredity

20. Thomas Hunt Morgan Evolution Post-1910 • Mendelian genetics, which he now embraced, provided an acceptable explanation for the origin of variation; • He supported natural selection • He supported common descent

21. The Fly Room The investigator must . . . cultivate a skeptical state of mind toward all hypothesis –especially his own- and be ready to abandon them the moment the evidence points the other way. T.H. Morgan, 1927

22. In 1933 Thomas Hunt Morgan was the first geneticist to be awarded the Nobel Prize. He received the prize for Physiology or Medicine for demonstrating that genes were located on chromosomes via hereditary transmission in Drosophila melanogaster

23. Undergraduate BiologyInstruction

24. Intended Learning Outcomes • Development of content knowledge in the areas of transmission genetics, molecular biology, evolution, natural selection, and population genetics; • Development of content knowledge and understanding of the history of biology; • Understanding that biology is an accumulated, yet impermanent body of knowledge.

25. Instructional Strategies Reading Significant Episodes in the History of Science

26. Instructional Strategies Engage Students with Phenomena

27. Instructional Strategies Challenge students to think about their ideas (create dissatisfaction)

28. Instructional Strategies Discussion of ideas theirs and those of others Student discussion Session

29. Discussion Questions • What is required to believe a concept or an idea? • What “got in the way” for Morgan to embrace Mendel’s ideas? • What does it mean to be an experimentalist? • What counts as evidence in a scientific investigation? • How does one know when enough data/evidence has been collected to support a theory? • What does it mean for information to be internally consistent? • What does it mean for information to be externally consistent?

30. Instructional Strategies Require students to justify their ideas; create written arguments grounded in and supported by data

31. General Biology IIStudent Assessment

32. Productive Synthesis Concept Map

33. Obstructive Synthesis Concept Map

34. Semi-Productive Synthesis Concept Map

35. What does this mean for biology instruction? • Biology instruction is enhanced and strengthened by the inclusion of history of science in the biology curriculum • Linking the history of biology, genetics, and evolution opens the door for students to “give up” their misconceptions • Linking the history of biology, genetics, and evolution enables students to construct their biology content knowledge and increases the likelihood of understanding both the process of science and the products it has produced • Knowledge of the history of biology aids students in understanding that biology (as well as the other sciences) is an accumulated, yet impermanent body of knowledge

36. Picture Resources • Kohler, R.E. (1984). Lords of the Fly: Drosophila Genetics and the Experimental Life. Chicago, IL: The University of Chicago Press • Hagen, J., Allchin, D. & Singer, F. (1996). Thomas Hunt & the White-eyed Mutant. In Doing Biology. New York, NY: HarperCollins College Publishers. • Edgewood College General Biology II students. • Campbell, N.A. & Reece, J.B. (2003). Biology, 6th ed. San Francisco, CA: Benjamin Cummings. • Google Images

37. Questions ?