NOTES WILL COVER:

• Evolution• Mutations• Natural Selection• Genetic Variations• Adaptations• Selective Breeding

Unit 2 :Chapter 10 : Section 3

Evolution

Many scientists believe that changes in the plants and animal species on earth can be explained by evolution.

Theory of EvolutionThe theory of evolution is the process by which populations accumulate inherited changes over time.

Unit 2 :Chapter 10 : Section 3

Mutations and Natural SelectionAccording to the theory of evolution, two processes are necessary for populations to change over time. These are mutations and natural selection.

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Mutations

• In order for a population to change, genes must be able to change

• Genes are made of DNA• DNA is made of 4 parts, called

nucleotides

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MutationsThe order of the nucleotides that are put together determines what characteristics you will receive from your parents.

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Mutations

Mutations can be harmful, helpful, or not change an individual at all

Changes in the type or order in which these bases appear are known as mutations.

Unit 2 :Chapter 10 : Section 3

Natural SelectionNatural selection is a word that Charles Darwin made very popular.

Unit 2 :Chapter 10 : Section 3

Natural SelectionAccording to Darwin’s theory, natural selection says that:

“organisms that are better able to survive and reproduce in an environment are more likely to pass their traits on to future generations”

Unit 2 :Chapter 10 : Section 3

1. Overproduction2. Genetic Variation3. Struggle to Survive4. Successful Reproduction

4 Steps of Natural Selection

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Natural Selection: Overproduction

• More individuals are born than will become adults

• Not all of these baby rats will become adults

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• The individuals in a population are NOT exactly the same

• Each has its own set of traits, such as size, color, and the ability to find food

Natural Selection:Genetic Variation

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Natural Selection:Genetic Variation

• Some traits make an individual more likely to survive and reproduce

• Other traits make survival and reproduction less likely

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Natural Selection:Struggle to Survive

• An environment might not be able to support all of the individuals born

• Also, many individuals are killed by other organisms

• Only some of the individuals in a population become adults and reproduce

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Natural Selection: Successful Reproduction

• The organisms that survive and reproduce have traits that are carried on by their many offspring

• This makes the “good” traits more dominant in the populations of individuals

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PracticeHow are the feathers of peacocks and the bright flowers of some plants related to successful reproduction?The feathers of peacocks attract mates. The bright coloring of some flowers attracts pollinators. Both of these traits increase the chances of successful reproduction.

Unit 2 : Chapter 14 : Section 2

Animals and Behavior• Innate behavior- a behavior that is influenced

by genes and does not depend on learning or experience

• Learned behavior- a behavior that has been learned from experience or observation

• Migrate- to travel from one place to another• Hibernation- a period of inactivity and lowered

body temperature that some animals experience in the winter

• Estivation- a period of reduced activity that some animals experience in the summer

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ADAPTATIONSThere are some traits among species that help to enhance the survival of those species

• Animals use many different methods to get food. Chimpanzees use sticks to get ants out of an anthill. This way they can get enough food while using the least amount of energy.

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ADAPTATIONS• Some animals use

camouflage to blend into the environment

• Some animals can drive other animals away by using external stimuli. Skunks use chemicals as external stimuli.

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ADAPTATIONS• Many animals are brightly colored

and use this external stimulus as warning coloration

• Often bright colored organisms are poisonous, and predators stay away from them

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Animals and BehaviorHibernation, estivation, and migration help many animals survive in harsh conditions.

Selective BreedingSelective BreedingSelective breeding is the process of breeding plants and animals for particular genetic traits

Examples: pigeons, dogs, and cattle