Natural SelectionNatural Selection

Natural Selection –Natural Selection –

• the processes by which individuals with favorable traits survive and reproduce, passing their traits on to the next generation.

Animals with unfavorable traits (ex. Animals with unfavorable traits (ex. poor eyesight, hearing, sense of poor eyesight, hearing, sense of

smell, etc.) therefore do not survive smell, etc.) therefore do not survive to pass on their genesto pass on their genes• .

Charles Darwin –Charles Darwin –• developed the theory of

natural selection. He believed that because of natural selection, these traits of survival accumulated in a population of a species and therefore allowed the species to adapt and flourish in its environment.

4 min

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4 Steps of Natural 4 Steps of Natural Selection:Selection:

• Overproduction

• Genetic Variation

• Successful reproduction

• Struggle to survive

Overproduction –Overproduction –

• organisms often have more offspring than could survive long enough to become adults

Genetic Variation –Genetic Variation –• No 2 organisms in any

population have the exact same traits. Some of these traits improve the chances the organism will survive (adaptations) and other traits lower the chances of survival.

Successful Reproduction –Successful Reproduction –

• organisms must be able to find a mate to reproduce and pass on their genes to the next generation.

Struggle to Survive –Struggle to Survive –• organisms within a population must compete for

food, water, and living space. Naturally, an environment cannot support ALL individuals in a population. Other individuals may be killed by predators or disease.

Obstacles to SurvivalObstacles to Survival• Naturally rare • Have specific food needs• Have specific nesting requirements• Interfere in some way with human activity• Sensitive to change• Has to compete with non-native species• Have small broods• Have long gestation period.

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