Theory of Evolution by Natural Selection

Biblical Reference Through him all things were made; without him nothing was made that has been made. John 1:3

Charles Darwin A naturalist is a person who studies plants and animals by observing them. naturalist Charles Darwin was an English naturalist who, in the mid-1800s, developed a theory of how evolution works.

The Galapagos Islands The Galapagos Islands are located 1,000 km off the South American coast in the Pacific Ocean. –Each island has a slightly different environment. –They vary in levels of humidity.

Charles Darwin Darwin found that tortoises looked different depending on which Galapagos Island environment they inhabited.

Darwin’s Theory Darwin also observed the differences among the mockingbird and finch populations throughout the islands. Darwin was convinced that the tortoises were from the same ancestors, but had become separated millions of years before and adapted to their food sources. –Long necks to reach tall cacti. –Short necks for short grasses. The birds also had similar adaptations.

Genetic Variations A variation is a slight difference in an inherited trait of individual members of a species.variation Variations arise naturally in populations, occurring in offspring as a result of sexual reproduction. Genetic changes to phenotype can be passed on to future generations.

Natural Selection Natural selection is the process by which populations of organisms with variations that help them survive in their environments live longer, compete better, and reproduce more than those that do not have the variations.Natural selection Natural selection explains how populations change as their environments change.

Natural Selection - Reproduction

Natural Selection - Variation

Natural Selection - Competition

Natural Selection - Selection

Adaptations Through natural selection, a helpful variation in one individual can spread to all members of a population. An adaptation is an inherited trait that increases an organism’s chance of surviving and reproducing in its environment.adaptation Adaptation comes from the from Latin word, adaptare, which means “to fit”.

Adaptations There are three types of adaptations: –Structural Adaptations –Behavioral Adaptations –Functional Adaptations

Structural Adaptation Structural adaptations involve color, shape, and other physical characteristics.

Behavioral Adaptation Behavioral adaptations involve the way an organism behaves or acts.

Functional Adaptation Functional adaptations involve internal body systems that affect biochemistry. The blood vessels in a jackrabbit’s ears expand to allow blood to cool.

Camouflage & Mimicry Camouflage and mimicry are adaptations that help species avoid being eaten. Camouflage is an adaptation that enables a species to blend in with its environment.Camouflage The resemblance of one species to another species is mimicry.mimicry

Camouflage

Mimicry

Artificial Selection The breeding of organisms for desired characteristics is called selective breeding.selective breeding Darwin realized that changes caused by selective breeding were much like changes caused by natural selection.

Which refers to the process by which populations of organisms with variations that help them survive in their environments live longer, compete better, and reproduce more than those that do not have the variations? Pop Quiz A.adaptation B.mimicry C.natural selection D.selective breeding

What term refers to the breeding of organisms for desired characteristics? Pop Quiz A.adaptation B.variation C.natural selection D.selective breeding

Which is an inherited trait that increases an organism’s chance of surviving and reproducing in its environment? Pop Quiz A.adaptation B.camouflage C.natural selection D.variation