Evidence for evolutionEvidence for evolution

Patrick LindPatrick LindPortland State UniversityPortland State UniversityProfessor Barbara ShawProfessor Barbara Shaw

Trilobite- http://everystockphoto.s3.amazonaws.comfossil_fossils_cambrian_327288_l.jpg

Evidence for evolutionEvidence for evolution

What did Charles Darwin (1809-1882) and others notice? What did Charles Darwin (1809-1882) and others notice?

•Huge variety of living thingsHuge variety of living things•Many similaritiesMany similarities•Fossils of animals now extinctFossils of animals now extinct•The earth could be very oldThe earth could be very old

http://www.darwin.ie/wordpress/wp-content/uploads/2008/02/darwin.jpg

BiodiversityBiodiversity

So many species exist. Why?So many species exist. Why?

Bird, flower, sea-worm-courtesy Patrick LindCheetah-http://www.uwyo.edu/dbmcd/molmark/lect11/Cheetah.jpgDragonfly-http://www.cssplay.co.uk/menu/slides/dragonfly.jpgSnail-http://www.animalwebguide.com/Snail-1.jpg

HomologyHomology

Some animals have very similar structures.Some animals have very similar structures.

Many vertebrates look Many vertebrates look and act very differently, and act very differently, but seem to be put but seem to be put together the same way. together the same way. (Homology) (Homology)

Forelimbs= “one, two, Forelimbs= “one, two, few, many”few, many”

Homology-http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=dbio&part=A69

Homology vs. HomoplasyHomology vs. Homoplasy

But some similar structures aren’t put together the But some similar structures aren’t put together the same way. Is one way better?same way. Is one way better?

Octopus eyeOctopus eyeHuman eyeHuman eye

In human eyes, the nerve fibers go in front of the In human eyes, the nerve fibers go in front of the retina, and there is a blind spot.retina, and there is a blind spot.

Eyes-http://en.wikipedia.org/wiki/Evolution_of_the_eyehttp://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2003/Muller/development%20of%20the%20cephalopod%20eye.htm

Developmental Homology Developmental Homology

The earliest stages of life The earliest stages of life (embryo) for related (embryo) for related animals look more similar animals look more similar than adult stages.than adult stages.

What similarities can you see?What similarities can you see?(There are gill pouches that we (There are gill pouches that we can’t see here).can’t see here).

Embryos-http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=dbio&part=A36 Embryos-http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=dbio&part=A36 Embryo hourglass-http://www.mk-richardson.com/pdf/Anat%20Embryol.pdfEmbryo hourglass-http://www.mk-richardson.com/pdf/Anat%20Embryol.pdf

ExtinctionsExtinctions

Fossil remains are known for animals that no Fossil remains are known for animals that no longer exist.longer exist.

DinosaurDinosaur

Gastornis Gastornis

TrilobiteTrilobite

MegatheriumMegatherium

Dinosaur fossil-http://static.howstuffworks.com/gif/dinosaur-images-Dinosaur fossil-http://static.howstuffworks.com/gif/dinosaur-images-064-resize.jpg064-resize.jpgDarwin’s Darwin’s Megatherium-http://www.christs.cam.ac.uk/darwin200/pages/index.Megatherium-http://www.christs.cam.ac.uk/darwin200/pages/index.php?page_id=c3php?page_id=c3Gastornis-http://en.wikipedia.org/wiki/File:Gastornis_skeleton.jpgGastornis-http://en.wikipedia.org/wiki/File:Gastornis_skeleton.jpg

UniformitarianismUniformitarianism

Darwin was influenced by Charles Lyell, who believed that slow Darwin was influenced by Charles Lyell, who believed that slow steady processes shape the earth. This meant that the earth steady processes shape the earth. This meant that the earth had to be had to be veryvery old. old.

http://www.talkorigins.org/faqs/precursors/precurstrans.htmlhttp://washingtonindependent.com/wp-content/uploads/2008/11/grand-canyon.jpghttp://brg.cma.nsw.gov.au/uploads///images/touchscreen/Severe%20gully%20erosion%20on%20dispersible%20solodic%20soils%20in%20the%20Yetman%20area%20MRC.JPG

LyellLyell

How long did it take the Colorado River to form the Grand How long did it take the Colorado River to form the Grand Canyon?Canyon?

Small gullySmall gully Giant canyonGiant canyon

ErosionErosion

UniformitarianismUniformitarianism

Darwin was influenced by Charles Lyell, who believed that slow Darwin was influenced by Charles Lyell, who believed that slow steady processes shape the earth. This meant that the earth steady processes shape the earth. This meant that the earth had to be had to be veryvery old. old.

http://www.talkorigins.org/faqs/precursors/precurstrans.htmlhttp://washingtonindependent.com/wp-content/uploads/2008/11/grand-canyon.jpghttp://brg.cma.nsw.gov.au/uploads///images/touchscreen/Severe%20gully%20erosion%20on%20dispersible%20solodic%20soils%20in%20the%20Yetman%20area%20MRC.JPG

LyellLyell

How long did it take the Colorado River to form the Grand How long did it take the Colorado River to form the Grand Canyon? >>>>>17 million years.Canyon? >>>>>17 million years.

Small gullySmall gully Giant canyonGiant canyon

ErosionErosion

Evidence for evolutionEvidence for evolution

Four observations needed an Four observations needed an explanation:explanation:

•BiodiversityBiodiversity•HomologyHomology•Fossil record (extinctions)Fossil record (extinctions)•Deep time (uniformitarianism)Deep time (uniformitarianism)

What did Darwin come up with?What did Darwin come up with?

Voyage of the Voyage of the Beagle Beagle (1831-1836) (1831-1836)

http://www.dailymail.co.uk/sciencetech/article-1084712/Darwins-Beagle-sail--5m-replica-survey-oceans-help-NASA-craft.htmlhttp://anthro.palomar.edu/evolve/evolve_2.htm

Darwin sailed to Patagonia where he collected fossils and living animals.

““Darwin’s Finches”Darwin’s Finches”

These birds seemed closely related, yet each was specialized for the small island it lived on.

Darwin’s big idea…Evolution by Natural Selection“Descent with modification”

Darwin shares credit for the idea with Alfred Russel Wallace.

Natural SelectionNatural Selection

1. Individuals compete for survival.1. Individuals compete for survival.

http://www.smithsonianmag.com/science-nature/Evolution-in-Black-and-White.htmlhttp://biology.fullerton.edu/life/im/kettlewell.jpg

Pocket micePocket mice

Peppered mothPeppered moth

2. Variation in a given trait is 2. Variation in a given trait is natural (mutation is source).natural (mutation is source).

3. Many traits are heritable.3. Many traits are heritable.

4. When a heritable trait helps an 4. When a heritable trait helps an individual reproduce more, that individual reproduce more, that trait becomes more common in the trait becomes more common in the next generation. next generation.

ExperimentExperiment

Modeling Natural SelectionModeling Natural Selection•You are the predator.You are the predator.•White and black beans are the pocket White and black beans are the pocket mice.mice.•Mice live on dark and light surfaces.Mice live on dark and light surfaces.•Any mouse that survives feeding Any mouse that survives feeding reproduces.reproduces.

We will “feed” on mice on both surfaces We will “feed” on mice on both surfaces and watch how populations change over and watch how populations change over time in each habitat. time in each habitat.

Predators will be rewarded Predators will be rewarded

InstructionsInstructions

1. Each student takes a cup for a “stomach” and a clothespin for a “beak.”

2. Evenly spread 50 black beans and 50 white beans over the black fabric.

3. Record the initial number of beans on your data sheet.4. When you hear “GO” start collecting as many beans as you

can.5. When you hear “STOP” put down you cups and clothespins.6. Reproduce. Place a new black or white bean next to every

surviving bean of the same color.7. Count the white and black beans and record in the appropriate

column.8. Repeat steps 4-7 as long as directed by the teacher.9. When directed, repeat the whole procedure, now using the

white fabric. Keep all your “mice” in your “stomach” for the reward.

10.Wait for instructions on graphing your data. Stopwatch

DiscussionDiscussion

• Did our mouse populations evolve in response to natural selection?

• In the mouse’s world, what is causing selection to occur?

• Did any individual mice change because of natural selection?

• If the mice were always all white or all black, would evolution occur?

• What types of errors could be affecting our results?

http://gallery.photo.net/photo/6090700-lg.jpg

Well done, predators.