unit 6: natural selection

Unit 6: Natural Selection

Galapagos Islands (Ecuador)

Charles Darwin visited these Islands in the 1830’s aboardThe HMS Beagle (painting above by Conrad Martens).

Darwin was cataloging species of a number of types of plants and animals, and he noticed that finches exhibited different sizes and shapes of beaks (Darwin’s drawing, above).

He hypothesized that they all originated from a common ancestor.

How does evolution happen?

Abzhanov, A.; Kuo, W. P.; Hartmann, C.; Grant, B. G.; Grant, P. R.: Tabin, C. J., “The calmodulin pathway and evolution of elongated beak morphology in Darwin's finches,” Nature 2006, 442, 563-567.

a, Developing avian beak is a three-dimensional structure that can change along any of the growth axes.

b, A beak of the sharp-beaked finch reflects a basal morphology for Geozpiza.

The model for BMP4 and CaM involvement explains development of both elongated and deep/wide beaks of the more derived species.

Abbreviations: C, caudal; D, dorsal; R, rostral; V, ventral.

For this seminar, you will simulate an example of natural selection with the words you use. When your instructor announces "START," you should have a chat about the weather in your area. The only hitch is that you may not use the letter 'e' in anything that you type. Any words that contain the letter 'e' will be ignored. You and your classmates will talk about the weather in your area for five minutes total, after which your instructor will announce "STOP," and you will be allowed to use the letter 'e' again.

Reflect on your conversation and discuss the following topics with your classmates:

1. In your new, 'e'-free environment, what adaptations to language did you and your classmates make?

WeatherThunderstormDrizzleIceHeavyClearFlurriesWater

HereAreaOutsideNeighborhoodState

In English, the most frequently appearing ten letters are e, t, a, o, i, n, s, h, r, and d, in that order, with the letter e appearing about 13% of the time.

Rflct on your convrsation and discuss the following topics with your classmats:

1. In your nw, ’e'-fr nvironmnt, what adaptations to languag did you and your classmats mak?

Unit 6: Natural Slction

WatherThundrstormDrizzlIcHavyClerFlurrisWatr

HrAraOutsidNighborhoodStat

In nglish, th most frquntly apparing tn lttrs ar e, t, a, o, i, n, s, h, r, and d, in that ordr, with th lttr e apparing about 13% of th tim.

2. What things were more difficult to talk about, and why?

3. If you were to live in a 'u'-free environment, what other letters might struggle and

die out?

4. Think about this experiment as a way to show how changes in environment force creatures (like you) to adapt and change. Now, think about squirrels. What might happen to them if all the oak trees (and therefore acorns) died out?

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4. Think about this experiment as a way to show how changes in environment force creatures (like you) to adapt and change. Now, think about squirrels. What might happen to them if all the oak trees (and therefore acorns) died out? What adaptations might they have to make to adjust to the acorn-free world?

4. Think about this experiment as a way to show how changes in environment force creatures (like you) to adapt and change. Now, think about squirrels. What might happen to them if all the oak trees (and therefore acorns) died out? What adaptations might they have to make to adjust to the acorn-free world? How might these changes affect their body structures?

4. Think about this experiment as a way to show how changes in environment force creatures (like you) to adapt and change. Now, think about squirrels. What might happen to them if all the oak trees (and therefore acorns) died out? What adaptations might they have to make to adjust to the acorn-free world? How might these changes affect their body structures? After 50,000 years of living in an acorn- free world, how might squirrels look? Why does this kind of evolutionary change take so long?

unit 6: natural selection

Documents

avian beak

natural selectionabzhanov

basal morphology

darwins finches

natural selectionunit

natural selectiondarwin

natural selectionhow

calmodulin pathway