Biology 101B

Evolution Unit

HISTORY OF EVOLUTION

What was Lamarck’s contribution to the

theory of evolution?• Lamarck- believed in things changing over

time, but he thought that things were changing towards “perfection” and that ACQUIRED traits could be INHERITED

• Idea of Use and Disuse

• Neither of these is true!

Sir Charles Lyell(1797-1875)

• Wrote Principles of Geology• Believed in gradualism-

gradual changes in environment led to gradual changes in organisms.

• Knew both Lamarck and Darwin, eventually supported Darwin more.

Alfred Russell Wallace(1823-1913)

• Wrote Darwin letters that prompted Darwin to finish his book- had same basic ideas as Darwin.

• Did his research on Malay Archipelago

• Sometimes called “Father of Biogeography”

• Verified Darwin’s ideas on “struggle for existence”

What was Darwin’s contribution to the theory of

evolution?• Scientist who was employed as a naturalist on

the Beagle (ship that traveled in South America)

• He collected many specimens in South America- especially in the Galapagos Islands

• Questioned why S. American island fossils were more similar to S. Amer. Mainland fossils than they were to North American fossils

• Read Lylle’s work and realized that the Earth’s surface was gradually changing and began to realize that the Earth was older than previously thought and was constantly changing

Cont’• Darwin found many separate islands

in the Galapagos• On each island there was a

predominant type of food (berries, nuts, insects, etc) for birds

• Each island had finches with different shaped beaks

• These were all very similar to the South American mainland Finch

• Darwin theorized that the mainland finches had migrated to each individual island and over a LONG period of time the beaks had become modified for the food on each island

• Called “Descent with Modification”

http://vimeo.com/47181679

Making of the Fittest

Fri 4/18What is Natural Selection?

• A population of organisms can change over generations IF individuals having certain heritable traits leave more offspring than others

• Mechanism by which evolution is proposed to occur

What are the 4 parts of Darwin’s Descent with Modification idea?

• Individuals within a population vary in their traits (all the shells are the same species- yet have many different shells)

• Traits are inherited

What are the other 2 postulates?• More offspring are

produced than can survive because of limited resources

(leads to competition)

• Individuals with advantageous traits will survive and reproduce (light grey moths on dark trees are eaten before they have a chance to reproduce- leads to decline in their number)

What are the two main features of Darwin’s View of Life?

• The diverse life forms of life have arisen by descent with modification from ancestral species

• The mechanism of modification has been natural selection working over large spans of time

How is Darwin important to the theory of evolution?

• Darwin came up with the idea of natural selection

• Developed 4 postulates of change that are still used today to explain how living things change over time

Today’s Assignments

1. Lactase Click and Learn- in MC

Quiz 3

1. What is “natural selection”?

2. How is artificial selection different?

3. What is a population?

4. In what sense is natural selection more of an “editing” process than a “creating” process?