Biology Chapter 15

Interest Grabber NOTEBOOK#1 ¡ A Trip Around the World

¡ While on his voyage around the world aboard the H.M.S. Beagle, Charles Darwin spent about one month observing life on the Galápagos Islands. There, he encountered some unique animals, such as finches and tortoises.

1. On a sheet of paper, list five animals that you have encountered in the past two days.

2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.)

3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands.

Section 1 Answers

Interest Grabber Answers

1. On a sheet of paper, list five animals that you have encountered in the past two days. Sample answers: dogs, cats, insects, snakes, birds, and so on.

2. How do these animals differ from the finches and tortoises of the Galápagos Islands? (Examine Figures 15–3 and 15–4 in your textbook.) Students may not see a noticeable difference between birds in their area and finches. However, the land tortoises, which are very large, would be very different from any turtles that students may have on their lists.

3. Propose a hypothesis to account for the differences between the animals that you observed and the finches and tortoises of the Galápagos Islands. Sample hypothesis: Animals become well suited to their surroundings.

Charles Darwin Charles Robert Darwin (12 February 12, 1809 – April 19, 1882) was an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection. He wrote the famous book Origin of Species.

Darwin’s Voyage- The HMS Beagle set sail from Plymouth Sound on December 27th, 1831 under the command of Captain Robert FitzRoy.

Galapagos Islands

¡ The Galapagos Islands were of special interest to Darwin

¡ Observations of Galapagos organisms supported Darwinʼ’s conclusion that evolution occurs

Giant Tortoises of the Galapagos Islands

Pinta Island Intermediate shell

Pinta

Isabela Island Dome-shaped shell

Hood Island Saddle-backed shell

Hood Floreana

Santa Fe

Santa Cruz

James

Marchena

Fernandina

Isabela

Tower

Galapagos Tortoises

Galapagos Animals

NOTEBOOK #2

1. Who was Charles Darwin?

2. What was the name of the ship he traveled around

the world on?

3. What book is he famous for writing?

4. What process is given credit for describing?

5.  List several animals found on the Galapagos

Islands.

Interest Grabber NOTEBOOK #3 ¡ My, How Youʼ’ve Changed!

¡  Prior to the 1800s, life scientists knew that living things changed over generations. They just didnʼ’t know how these changes were brought about.

1. Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair.

2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument.

3. Which of the items in your lists do you think you might pass on to your children? Explain your answer.

Section 2 Answers

Interest Grabber Answers

1. Divide a sheet of paper into two columns and title the first one Inherited Characteristics. Title the second column Acquired Characteristics. In the first column, list the characteristics that you believe you have always had. For example, you may have brown eyes or curly hair.

Students should list traits that are genetically influenced.

2. In the second column, list your acquired characteristics. For example, you may have learned how to play a musical instrument.

Remind students that many features, including skills, appearance, and athletic ability, can be changed to some degree by effort.

3. Which of the items in your lists do you think you might pass on to your children? Explain your answer.

Genetically influenced traits are passed on. Some items, such as musical or athletic talent, may have both inherited and learned components.

Lamarck’s Theory of Evolution

Lamarck believed that the long necks of giraffes evolved as generations of giraffes reached for ever higher leaves.

Lamarkism is the idea that an organism can pass on characteristics that it acquired during its lifetime to its offspring (also known as heritability of acquired characteristics or soft inheritance).

Jean-Baptiste Lamarck

Lamarck

¡ Law of Use and Disuse- Lamarck thought that characteristics could be obtained or lost as a result of use and disuse

¡ The “changed” feature was called an acquired characteristics

¡ Lamarck thought that acquired characteristics were passed on to the offspring of the individual

Concept Map

includes

Evidence of Evolution

Physical remains of organisms

Common ancestral species

Similar genes Similar genes

which is composed of which indicates which implies which implies

The fossil record

Geographic distribution of living species

Homologous body structures

Similarities in early

development

Geographic Distribution of Living Species

Beaver

NORTH AMERICA

Muskrat

Capybara SOUTH AMERICA

Coypu

Beaver

Muskrat

Beaver and Muskrat

Coypu

Capybara

Coypu and Capybara

Homologous Body Structures - HOMOLOGOUS STRUCTURES are body parts that are structurally similar in related species; these provide evidence for a common ancestor. These homologous structures are also linked to common DNA.

Turtle Alligator

Bird Mammal

Ancient lobe-finned fish

Notebook #4

1. Who was Jean-Baptist Lamark? 2. What was the basis for his theory of

evolution? 3. How was his theory different from

Charles Darwin’s theory? 4. What are homologous structures?

Interest Grabber – Notebook #5

¡ Yes, No, or Maybe

¡ Some traits, such as a widowʼ’s peak, fall into neat categories: You either have a widowʼ’s peak or you donʼ’t. Other traits, such as height, arenʼ’t so easy to categorize.

Interest Grabber ¡  1. Make a list of physical traits that you

think are influenced by genes. Then, write next to each trait whether you have the trait or not (e.g., a widowʼ’s peak) or whether there are many variations of the trait (e.g., hair color).

¡  2. Are most of the traits you listed clear-cut or are they mostly traits that have many variations? Which traits in your list are difficult to categorize?

¡  3. Compare your list with that of another student. Did he or she think of any traits that you missed? Why do you think some traits are clear-cut, while others are not?

Section 1 Answers

Interest Grabber Answers

¡  1. Make a list of physical traits that you think are influenced by genes. Then, write next to each trait whether you have the trait or not (e.g., a widowʼ’s peak) or whether there are many variations of the trait (e.g., hair color).

¡  Studentsʼ’ answers will include dimples and detached earlobes.

¡  2. Are most of the traits you listed clear-cut or are they mostly traits that have many variations? Which traits in your list are difficult to categorize?

¡  Most traits listed likely have many variations.

¡  3. Compare your list with that of another student. Did he or she think of any traits that you missed? Why do you think some traits are clear-cut, while others are not?

¡  Some students may suggest that patterns of inheritance for traits with many variations (polygenic) are more complex than for clear-cut (single-gene) ones.

Fossil Record

¡ Earthʼ’s history can be divided into eras and periods.

¡ Organisms that no longer exist are said to be extinct

http://www.naturalworlds.org/thylacine/index.htm�

http://listverse.com/2009/07/25/10-recently-extinct-animals/

fossil record: geologic time scale with major evolutionary events

Vestigial Organs ¡ Certain structures have no functions and are called vestigial organs

Evolution- is change with time. Mutation and genetic recombination could be called the “raw materials” of evolution.

Relative Frequencies of Alleles – some alleles occur more frequently in populations

Sample Population

48% heterozygous

black

36% homozygous

brown

16% homozygous

black

Frequency of Alleles

allele for brown fur

allele for black fur

Phenotypes for Single-Gene Traits

Fre

qu

en

cy

of P

he

no

typ

e

(%)

100

80

60

40

20

0 Widowʼ’s

peak No widowʼ’s

peak Phenotype

NOTEBOOK # 6

1.  What does it mean to be extinct? 2.  Why were new eras and periods created on the Geologic time

scale? 3.  What is a vestigial organ? Name one. 4.  What is evolution? 5.  Do all alleles occur at the same frequency in a population?

Interest Grabber – NOTEBOOK #7 ¡  . . . All the Help I Can Get

¡ Natural selection operates on traits in different ways. You might be able to predict which traits natural selection would favor if you think about the demands of an organismʼ’s environment.

1. Choose an animal that you know something about, such as a deer, and write its name at the top of a sheet of paper. Then, divide your paper into two columns, and write the heading Trait in one column and Advantage in the other.

2. Under Trait, write in several of the animal’s traits.

3. Under Advantage, write in how you think the trait would be helpful to the animal.

Section 2 Answers

Interest Grabber Answers

1. Choose an animal that you know something about, such as a deer, and write its name at the top of a sheet of paper. Then, divide your paper into two columns, and write the heading Trait in one column and Advantage in the other. Animal choices should be sufficiently familiar that students can describe several traits.

2. Under Trait, write in several of the animal’s traits. Students should list traits such as size, color, and specialized behavior.

3. Under Advantage, write in how you think the trait would be helpful to the animal. Students should indicate that adaptive value is clearer for some traits than for others. For example, white-tailed deer raise their tails upon sensing a predator. This may be an alarm signal for other deer, or it may induce the predator to chase the now-conspicuous deer.

Genetic Drift - The process of change in the genetic composition of a population due to chance or random events.

Sample of Original Population

Founding Population A

Founding Population B

Descendants

Directional Selection - is a mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction.

Directional Selection

Food becomes scarce.

Key

Low mortality, high fitness

High mortality, low fitness

Disruptive Selection - Extreme values for a trait are favored over intermediate values.

Disruptive Selection

Largest and smallest seeds become more common.

Nu

mb

er o

f Bird

s in

Po

pu

latio

n

Beak Size

Population splits into two subgroups specializing in different seeds.

Beak Size

Nu

mb

er o

f Bird

s in

Po

pu

latio

n Key

Low mortality, high fitness

High mortality, low fitness

Stabilizing Selection -is the opposite of disruptive selection, instead of favoring individuals with extreme phenotypes, it favors the intermediate variants.

Key

Perc

en

tag

e o

f Po

pu

latio

n

Birth Weight

Selection against both

extremes keep curve narrow and in same

place.

Low mortality, high fitness

High mortality, low fitness

Stabilizing Selection

NOTEBOOK # 8

1. What is genetic drift? 2. What is directional selection? 3. What is disruptive selection? 4. What is stabilizing selection?

Interest Grabber – NOTEBOOK #9 ¡ Country Cousin/City Cousin

¡ What happens when a population or group of living things is divided into two separate groups in two separate environments? To understand what goes on, think about someone who lives in another part of the United States or in another country.

1. Make a list of everyday things that this person encounters that you don’t. For example, does he or she eat different kinds of food? Does he or she live in a climate different from yours?

2. All humans are the same species. What might happen if groups of humans were separated for millions of years in very different environments, such as those you have just described?

Section 3 Answers

Interest Grabber Answers

1. Make a list of everyday things that this person encounters that you don’t. For example, does he or she eat different kinds of food? Does he or she live in a climate different from yours? Students’ lists should include several social/environmental factors.

2. All humans are the same species. What might happen if groups of humans were separated for millions of years in very different environments, such as those you have just described? Students may understand that humans would evolve separately in response to different environmental pressures.

Concept Map

Section 16-3

results from

which include

produced by produced by produced by

which result in

which result in

Reproductive Isolation

Isolating mechanisms

Behavioral isolation Temporal isolation Geographic isolation

Behavioral differences Different mating times Physical separation

Independently evolving populations

Formation of new species

NOTEBOOK #10

1. Explain how the theory of evolution links together all fields of science.