Evolution & Selection Modified from parts of a presentation by Diane Ebert-May Michigan State University

Where does life come from? Where do we come from? - one of ultimate human questions One of humanity’s traits is to ask, and try to answer, such questions – stories of Creation… With more knowledge, more understanding, our ideas change – tools of science

What is Evolution? In your notes – write down words or phrases that come to mind when you hear this word Share your ideas with your group members, and combine ideas to create a definition you can share with the class. 3 minutes!

What is Evolution? Simple biological definition: “Change in the frequency of genes and chromosome configurations in a population.” (Wilson ch. 6, p. 75) What does this mean? Discuss in your group, & come up with an answer (or a question). This simple definition is pretty hard to refute Such changes are happening all the time – via random mutation, & sorting during reproduction, and in response to a constantly changing environment… Last point is to see if they’re getting the gist of this def. – some won’t, I’m sure.

What drives evolution? Wilson ch. 6 Our main topic for today Will be ultimately addressing diff. “selective forces” that drive evolution: {artificial selection (humans) natural selection (environment) “genetic drift” – or chance – e.g. founder effect, bottleneck… (Wilson ch. 6 p. 81)} But don’t mention these yet!

Write a scenario that explains the phenotypic changes in the trees and the animals. Use your understanding of evolution by natural selection. Write response on carbonless paper, & put original in your folder for now – keep copy in your notes for future reference. 2 minutes! Is there some variation in these populations? Why…? Review

Close your eyes & vote… (since we don’t have clickers) Then give the answer – A. 1 Why?

Points: 1 – biological sp. concept 2 – whatever… 3 – examples…. What is the source(s) of this variation??

Apply those ideas from previous slide…

Why does this work? Variation must be heritable!! ARTIFICIAL SELECTION – who (or what) is doing the “selecting?”

All from one species – Brassica oleracea

Look @ photos & generate some hypotheses in your group (what are the main parts of a plant??): root – stem – leaf– flower – fruit - seed – (bud/shoot)

pictures IF get specimens, do this – but write it in your notes

What is phenotype? How does a phenotype change? (chng in genotype) SO - According to Wilson’s definition, has evolution occurred in either of the 2 examples we just went thru? (dogs & brocolli) (“Change in gene/chromosome configuration in pop.; chng. in gene frequency”) NEW TERM: Fitness

Moving away from artificial selection on to natural selection… Groups:discuss, come to consensus & report your response to class; justify

Why type of food??

Diff. “selective forces” that drive evolution: artificial selection (humans) natural selection (environment) “genetic drift” – or chance – e.g. founder effect, bottleneck… (Wilson ch. 6 p. 81) ?= put this info into another slide after last finch slide?...

How might these 8 diff. species have ended up on Hawaii, so far from the mainland? Remember Krakatau Remember ideas of speciation, geographic isolation, & put that together with selective forces – Evolution is always occurring; & new species sometimes form as a side effect of evolution… (remember vertical change vs. branching evol.)

Selective Agents or Forces: Artificial selection (selective agent is?) Humans Natural selection (selective agent is?) The Environment Genetic drift (there is no selective agent…) Occurs by chance – random change

Wrap-Up: At what “levels” do selection & evolution occur? Look at your hierarchy of terms linking DNA to species Where would you add the term “population?” Which level in this hierarchy gets selected for or against by the selective agents we’ve discussed today? Now - at what level does evolution occur?

Write a scenario that explains the phenotypic changes in the trees and the animals. Use your understanding of evolution by natural selection. Make your own notes, then come up with one written response for your group that all agree upon & understand. Put original in folder. Write response on carbonless paper, & put original in your folder for now – keep copy in your notes for future reference. 2 minutes! Is there some variation in these populations? Why…? Review