Unit 5 – Lecture 3

Types of EvolutionMacroevolution

change of one kind of organism into another“macro” = largethis has not been observed, but is assumed in

the current evolutionary theory

Types of Evolution – cont’dMicroevolution

small changes in organisms through selection“micro” = smallhas been observedis assumed in in current evolutionary theory to

accumulate until a large change is seen

Discuss

Explain the difference between macro- and micro- evolution

SelectionExample to be used:

A colony of clams lives at a particular beach. These clams come in three varieties – white, grey, and black. Grey is, of course, an intermediate color between the two extremes, white and black. These clams are a part of a sea-bird’s natural diet – however, they are unable to see the clams well which blend into the background of the sand and rock underneath. The beach contains areas of light, dark and intermediate sand in various amounts.

Natural SelectionNatural Selection – organisms which have the

best-suited traits survive in their environment

Natural Selection – cont’dNatural Selection – organisms which have the

best-suited traits surviveFour types:

directional selectionone extreme of a trait is best and is

selected

Natural Selection – cont’dNatural Selection – organisms which have the

best-suited traits surviveFour types:

disruptive selectionmultiple extremes of a trait are best and

are selected

Natural Selection – cont’dNatural Selection – organisms which have the

best-suited traits surviveFour types:

stabilizing selectionintermediate/average form of trait is

selected

Natural Selection – cont’dNatural Selection – organisms which have the

best-suited traits surviveFour types:

sexual selectionpresence of a trait influences mating trait can be physical OR behavioral

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Discuss

Name and describe the four types of natural selection.

Give an example of each typeof selection [NOT my example –

pick another]

Artificial SelectionArtificial Selection – humans select desirable

traits and breed out non-desirable traitscrop farming

Artificial Selection – cont’dArtificial Selection –

humans select desirable traits and breed out non-desirable traitsanimal breeding

Discuss

What is the difference betweennatural and artificial selection?

Selection – cont’dSelection works on POPULATIONS not on

individualswe do not select the best corn plant just to

plant one seed and make one plant!!just so, one animal with new

characteristics must cause change to the entire population for it to make a difference

HomeworkComplete the Darwin’s Five points worksheet

title of worksheet = “Natural Selection”

Label your MATERIALS check list with 2/8material = 3 Tabs

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