Chapter Menu Lesson 1 Natural Selection Lesson 2

Chapter Menu Lesson 1: Natural Selection Lesson 2: Adaptation and Extinction Click on a hyperlink to view the corresponding lesson.

5. 1 Natural Selection evolution naturalist natural selection adaptation

5. 1 Natural Selection Charles Darwin • Evolution is change over time. • The naturalist Charles Darwin was the first person to write a thorough collection of evidence supporting evolution. • Darwin’s theory serves as the basis of all biological research today.

5. 1 Natural Selection Charles Darwin (cont. ) • Darwin explored South America and its remote islands, such as the Galapagos, on the HMS Beagle.

5. 1 Natural Selection Darwin’s Observations • Darwin made observations about the diversity and uniqueness of organisms. – Many of the animals on the Galapagos were similar, but not the same as organisms in mainland South America. – Darwin reasoned that perhaps the organisms in the Galapagos originally came from South America and over time, they had evolved.

5. 1 Natural Selection Tortoises • Darwin found giant tortoises on all the Galapagos Islands, but nowhere else. • He reasoned that each new population changed slightly, or evolved, to fit its unique environment on the island.

5. 1 Natural Selection Finches • Darwin was impressed by the diversity of finches on the Galapagos. – Darwin explained that if individuals from a species were separated, future generations might look and behave differently. – The finches became different because they became suited to the different habitats on the islands.

5. 1 Natural Selection Selective Breeding • Selective breeding is breeding plants and animals to get offspring with desired characteristics. • This does not lead to a new species— the organism can still breed with other members of its species.

5. 1 Natural Selection Darwin’s Theory of Natural Selection • Organisms with traits that allowed them to survive under particular environmental conditions produced more offspring. • Eventually those traits would be common in the species. How can natural selection be modeled?

5. 1 Natural Selection Genetic Variation • Sometimes changes occur in genes and a new trait is created. • If the trait is beneficial, the organism may survive and pass the trait on to the next generation. • Genetic variation is necessary for evolution to occur.

5. 1 Natural Selection Population Growth and Struggle to Survive • Although resources are limited, animals often produce more offspring than could survive. • Darwin decided this was a natural process that selected which organism survived, and called it natural selection. • Adaptation refers to traits that increase the likelihood of surviving and reproducing in a particular environment.

5. 1 Natural Selection • Four steps or requirements of Darwin’s theory of evolution by natural selection: – Step 1: Overproduction – Step 2: Relative similarity – Step 3: Inherited variation – Step 4: Natural selection

5. 1 Natural Selection (cont. ) Overproduction Inherited Variation Natural Selection

5. 1 Natural Selection 1. 2. 3. 4. A B C D What did Darwin observe about the tortoises and finches in the Galapagos? A their large size B their similarity to those on the mainland C their adaptations to their environments D their friendliness

5. 1 Natural Selection 1. 2. 3. 4. A B C D What is necessary for evolution to occur? A selective breeding B genetic variation C populations isolated on islands D none of the above

5. 1 Natural Selection 1. 2. 3. 4. A B C D What is not a main source of genetic variation? A differences in diet B sexual reproduction C mutations D gamete formation

5. 2 Adaptation and Extinction structural adaptation camouflage mimicry behavioral adaptation extinct

5. 2 Adaptation and Extinction Adaptations • Humans can change their environment to meet their needs. • Organisms have evolved adaptations to their environment by the process of natural selection.

5. 2 Adaptation and Extinction Understanding Adaptations • Adaptations are inherited traits that increase an organism’s chance of surviving and reproducing in a particular environment. – Adaptations are the final products of the long process of natural selection. – Adaptations are naturally selected for, not intentional. – Not all traits are adaptations.

5. 2 Adaptation and Extinction Types of Adaptations • Structural adaptations are aspects of the physical body that help organisms survive and reproduce. • Camouflage—coloring that blends with the environment—makes organisms difficult to see.

5. 2 Adaptation and Extinction Types of Adaptations (cont. ) • Mimicry is when one species (the mimic) looks like another species (the model) in order to deceive a third species. • Behavioral adaptations are actions or behaviors that help organisms survive and reproduce.

5. 2 Adaptation and Extinction • A species becomes extinct when all the individuals of a particular species die off. • There have been several major extinction events in history.

5. 2 Adaptation and Extinction Causes of Extinction • Loss of habitat • Loss of genetic diversity • Competition with exotic species • Inability to adapt Causes of Slow Extinction

5. 2 Adaptation and Extinction 1. 2. 3. 4. A B C D What is not an example of an adaptation? A inbreeding B camouflage C mimicry D behavior

5. 2 Adaptation and Extinction 1. 2. 3. 4. A B C D Why do some non-desirable traits remain in a population? A selective breeding B mutation C they are genetically linked to more beneficial traits D they may be useful in the future

5. 2 Adaptation and Extinction 1. 2. 3. 4. A B C D What cause for extinction would most likely be involved in rapid environmental changes such as climate change? A loss of habitat B inability to adapt C loss of genetic diversity D competition with exotic species

Chapter Resources Menu Chapter Assessment California Standards Practice Image Bank Science Online Interactive Table Virtual Lab Click on a hyperlink to view the corresponding feature.

1. 2. 3. 4. A B C D What is evolution? A adaptations to particular environments B genetic change in a population over time C natural selection D differences in traits

1. 2. 3. 4. A B C D What is necessary for natural selection to occur? A genetic variation B constant environmental conditions C isolate populations D shortage of offspring

1. 2. 3. 4. A B C D Which of the following is NOT one of the main sources of genetic variation in a population? A mutations B learned abilities C formation of gametes D sexual reproduction

1. 2. 3. 4. A B C D Which of the causes of extinction is not influenced by human actions? A inability to adapt B loss of genetic diversity C loss of habitat D competition with exotic species

1. 2. 3. 4. A B C D Why do desert rabbits have mottled fur? A behavioral adaptations B mimicry C camouflage D incomplete dominance

SCI 3. a 1. 2. 3. 4. A B C D What causes evolution? A genetic variation B environmental factors C both D neither

SCI 3. e 1. 2. 3. 4. A B C D What is one reason exotic species can sometimes outcompete native species? A they have no natural predators B there are more of them C the new environment is more favorable D the natives are not adapted

SCI 3. e 1. 2. 3. 4. A B C D When do we designate a species as threatened or endangered? A when there is one population left B when the number of individuals falls below a certain level C when population numbers are declining D when genetic variation is low

SCI 3. a 1. 2. 3. 4. A B C D Which is required for natural selection to occur? A inherited variation B overproduction of offspring C genetic variation D all of the above

SCI 3. b 1. 2. 3. 4. A B C D Which of the following did not contribute to Darwin’s development of theory of natural selection? A overproduction of offspring B competition with exotic species in the Galapagos C an essay on human population growth D similarities and differences of species in the Galapagos

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Interactive Table Causes of Slow Extinction