INTRODUCTION TO EVOLUTIONCHAPTER 15

THEORIES OF EVOLUTION

SECTION 15-2

LAMARCK’S EXPLANATIONStated that animals evolved by passing on acquired traits.

Was proven to be incorrect – why?

CHARLES DARWINDarwin’s theory revolved around Natural Selection.

Believed that species evolved by this process in specific populations.

DARWIN’S JOURNEYSailed on a ship called the HMS Beagle.

Mainly gathered data in South America.

Studied one species of bird in particular – what was it?

DARWIN’S BOOKDarwin’s Book: The Origin of Species was published in 1858.Why is it still important to us?

DARWIN’S THEORIESDescent with Modification:

• Today’s species came from relatives from a long time ago.

Modification by Natural Selection:• Explained why evolution happens.

MORE ABOUT NATURAL SELECTIONWhat does natural selection mean to you?

What did Darwin say was the main reason for populations changing?

NATURAL SELECTION CONTINUED…The only way that an individual can pass on their traits is to …

Survival of the fittest doesn’t necessarily mean the fastest, strongest or smartest! (Look at #7 on worksheet from Thursday)

STILL MORE ON NATURAL SELECTIONA species must adapt to a changing environment.Think about the game we played online “Who Wants to Live a Million Years?”

• What changes happened?• How did your species adapt?• Did you see changes happening all the time?• What did you do to help your species survive?

ARTIFICIAL SELECTIONIn the beans lab – what were you artificially selecting for?Why did the population start to change as you went through more generations?What are some reasons that artificial selection can be detrimental to a species?

BEAN LABWhy did you have to take 2 beans each time you chose?

• They represent …What are other things that you could have artificially selected for?Do we have the power to artificially select for genotypes and phenotypes?

EVIDENCE OF EVOLUTION

SECTION 15-3

HOMOLOGOUS STRUCTURESDefine homologous structures in your own words (remember the x-ray activity we did).

How do homologous structures provide evidence for evolution?

ANALOGOUS AND VESTIGIAL STRUCTURESAnalogous structures are different than homologous structures because…

Vestigial structures are no longer useful to the current species but were once useful to earlier species.

• Give at least two examples of a vestigial structure.

PATTERNS OF EVOLUTION

COEVOLUTIONThe change of two or more species in close association with each other.

Example: Newts and garter snakes

1. Why has the newt developed a level of toxicity much higher than that necessary to kill most predators? 2. What is the selective pressure on the newt?3. What is the trade-off for the snake in developing greater resistance to toxicity?

CONVERGENT EVOLUTIONOccurs when the environment selects for similar phenotypes, even though the ancestral types were quite different from each other.

Example: Sharks and Porpoises

DIVERGENT EVOLUTIONWhen related populations or species become more and more dissimilar.Usually related to different habitats.

Adaptive radiation: When many related species evolve from a single ancestral species.

Also can be caused by natural selection!

WHY DOES EVOLUTION MATTER TO US?Evolution

1. How do humans influence the evolution of microbes?2. How does natural selection work to produce multi-drug-resistant tuberculosis? 3. Why is understanding evolution especially important today, now that people can travel easily?

QUIZ TOMORROW!Suggested Questions to study from:

pg. 288: 1, 3, 5, 6pg. 292: 1, 2, 6pg 294: 3, 4, 5, 6, 8, 9, 10, 11, 12, 13, 14, 21, 22, 25 & Critical Thinking 1, 2