Chapter 3

Objectives

• Identify three kinds of adaptations that help organisms survive.

• Describe the four parts of natural selection.

• Explain Explain how variation occurs within a population.

Section 4 Adaptation and Survival

Chapter 3

Objectives, continued

• Explain why genetic variation within a population is important.

• Explain how resistance to insecticide is a survival characteristic.

Section 4 Adaptation and Survival

Chapter 3

Adaptations for Obtaining Food

• An adaptation is a characteristic that improves an individual’s ability to survive and reproduce in a particular environment.

• Almost all organisms have adaptations to help them obtain food.

Section 4 Adaptation and Survival

Chapter 3

Predator-Prey Adaptations

• Many organisms also have adaptations that serve as a defense against predators.

• One common adaptation that helps predators and prey is called camouflage. An organism that is camouflaged is disguised so that it is hard to see even when the organism is in view.

Section 4 Adaptation and Survival

Chapter 3

Adaptations to Interactions

• Two species can also acquire adaptations because of their interaction with one another.

• Adaptations because of interactions can take place between any organisms that live close together.

Section 4 Adaptation and Survival

Chapter 3

Natural Selection

• Inherited characteristics in populations can change over time.

• Natural selection is the process by which individuals that are better adapted to their environment survive and reproduce more successfully than less well-adapted individuals do.

Section 4 Adaptation and Survival

Chapter 3

• The theory of natural selection explains how a population changes in response to its environment.

• If natural selection is always taking place, a population will tend to be well adapted to its environment.

• The individuals that are likely to survive and reproduce are those that are best adapted at the time.

Natural Selection, continued

Section 4 Adaptation and Survival

Chapter 3

Natural Selection, continued

Section 4 Adaptation and Survival

Chapter 3

Changes in Genetic Variation

• In order for natural selection to continue, individuals within the population must be different.

• Over time, the population will be made up of more individuals with characteristics that help them survive.

• If a population decreases rapidly, a genetic bottleneck occurs. Many characteristics may be lost entirely from a population because all of the individuals with those characteristics died.

Section 4 Adaptation and Survival

Chapter 3 Section 4 Adaptation and Survival

Chapter 3

Insecticide Resistance

• Insecticide resistance is also a result of natural selection.

• Some individual insects within a population are resistant to certain insecticides. Resistance is an adaptation.

• These insects survive and reproduce. They pass the insecticide-resistance genes to their offspring.

Section 4 Adaptation and Survival

Chapter 3 Adapting to the Environment

Use the terms below to complete the concept map on the next slide.

asexual reproduction buddingexternal fertilization fragmentationreproduction internal fertilizationsexual reproduction

Concept Mapping

Chapter 3 Adapting to the Environment

Chapter 3 Adapting to the Environment