Unit 5 – Lecture 3
Types of Evolution
 Macroevolution
 change of one kind of organism into another
 “macro” = large
 this has not been observed, but is assumed in the
current evolutionary theory
Types of Evolution – cont’d
 Microevolution
 small changes in organisms through selection
 “micro” = small
 has been observed
 is assumed in in current evolutionary theory to
accumulate until a large change is seen
Discuss
 Explain the difference between
macro- and micro- evolution
Selection
 Example 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 Selection
 Natural Selection – organisms which have the
best-suited traits survive in their environment
Natural Selection – cont’d
 Natural Selection – organisms which have the best-
suited traits survive
 Four types:
 directional selection
 one extreme of a trait is best and is selected
Natural Selection – cont’d
 Natural Selection – organisms which have the best-
suited traits survive
 Four types:
 disruptive selection
 multiple extremes of a trait are best and are
selected
Natural Selection – cont’d
 Natural Selection – organisms which have the best-
suited traits survive
 Four types:
 stabilizing selection
 intermediate/average form of trait is selected
Natural Selection – cont’d
 Natural Selection – organisms which have the best-
suited traits survive
I made these
 Four types:
just for YOU!
 sexual selection
 presence of a trait influences mating
 trait can be physical OR behavioral
La la la la la la la
la laaaaaa!!!!!!
Discuss
 Name and describe the
four types of natural selection.
 Give an example of each type
of selection [NOT my example –
pick another]
Artificial Selection
 Artificial Selection – humans select desirable traits
and breed out non-desirable traits
 crop farming
Artificial Selection – cont’d
 Artificial Selection –
humans select desirable
traits and breed out
non-desirable traits
 animal breeding
Discuss
 What is the difference between
natural and artificial selection?
Selection – cont’d
 Selection works on POPULATIONS not on individuals
 we 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
Homework
 Complete the Darwin’s Five points worksheet
 title of worksheet = “Natural Selection”
 Label your MATERIALS check list with 2/8
 material = 3 Tabs
 Take our your transcript, I will call you up in a minute.