Geology 12 - Historical Geology

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Evolution

Reading: Chapter 3

p. 42-45: Skim this section just for an overview of early theories of evolution. We are interested primarily in the mechanism of natural selection.

Background

Terms you should know:

phylogeny -

punctuated equilibrium-

phyletic gradualism-

speciation -

founder effect-

homology-

Key Concepts and Questions:

1. What is the difference between evolution and natural selection?

Define evolution:

Define natural selection:

2. What are the necessary conditions for natural selection to operate?

a. There must be variation in the population.

What are two potential sources of new variation in populations?

b. The variable traits must lead to differential reproduction. This means organisms with one variant of the trait must be able to reproduce and rear their offspring tor eproductive age more successfully than organisms with a different variant of the trait.

Find two examples in the book of traits that lead to differential reproduction.

c. The trait must be passed on to the offspring.

What is the mechanism by which traits are passed to offspring?

3. How can natural selection lead to new kinds of organisms?

What is a species?

How do new species form? Find two mechanisms for speciation in the book.

What is the difference between the two models of speciation, phyletic gradualism and punctuated equilibrium?

4. What is the evidence that evolution has occurred?

Find at least three lines of evidence that lead Darwin to propose his model of natural selection.

Assessment

1. Evolution v. natural selection

You should be able to:

define evolution and natural selection, and cite examples of each
distinguish between the two

2. Conditons for natural selection

You should be able to:

identify and describe the necessary conditions for natural selection
explain the origin of variation in populations
use natural selection to explain the origin of features in organisms

3. Species

You should be able to :

describe two mechanisms for the origin of species
describe the difference between phyletic gradualism and punctuated equilibrium
recognize from a fossil lineage when phyletic gradualism or puntuated equilibrium may have occurred

4. Evidence of evolution