THE EVOLUTION OF LIVING THINGS Objectives Explain how

THE EVOLUTION OF LIVING THINGS.

Objectives ü Explain how fossils provide evidence that organisms have evolved over time. ü Explain how organisms can be compared to support theory of evolution.

Objectives ü Describe Charles Darwin and his theory of natural selection. ü Explain how mutations are important to evolution. ü Provide examples of natural selection in action. ü Outline the process of speciation

Evolution I. Evolution – the process by which organisms accumulate inherited changes over time. A. Scientists believe that all living things share a common ancestor – bacteria. B. Charles Darwin – determined how evolution occurred by studying finches in the Galapagos islands.

C. Adaptations – characteristics that allow or help an organism survive and reproduce. 1. Examples – frog coloring, beak shape, ear size. 2. Allows some organisms to survive and reproduce at a greater rate than other organisms.

Adaptations

EVIDENCE How do we know evolution has occurred? I. Evidence of Evolution: Why do scientists believe that evolution occurs? A. Fossils: solidified remains or imprints of once living organism. Scientists use the layers of sediment to determine the relative age of fossils. B. Vestigial Structures: Remnants of once useful

EVIDENCE C. Comparing Organisms: Shows similarities among organisms. 1. skeletal structures – dolphin flipper, bat wing, human arm, cat leg 2. DNA – all organisms have DNA; many organisms have similar codes 3. embryonic structures – chicken, rabbit, human

Layers of Sediment

Vestigial Structure

Similar Skeletal Structures

Similar DNA http: //www. genome. gov/15515096

Embryonic Structures

Natural Selection – a process in which organisms with favorable traits survive and reproduce at a greater rate

A. Four stages 1. Overproduc tion – produce more offspring than will survive to maturity. 2. Genetic variation – all organisms within a population are slightly different than one another.

3. Struggle to Survive organisms compete and ones with favorable traits survive and reproduce. 4. Successful Reproduction – Those individuals that are well adapted and have traits that help them survive in their environment are more likely to survive and reproduce.

Mutations B. Mutations – a change in the sequence of the DNA that causes variation within the species.

Ways it occurs… C. Natural Selection in Action 1. Insecticide Resistance - farmers use insecticide. Insects resist and reproduce.

2. Adaptation to pollution - Peppered Moth Story

How did there become so many species? 3. Speciation - Two populations become so different they can no longer interbreed. a. Separation – portion of population is physically isolated (earthquake, Pangaea, canyons, etc. ) b. Adaptation - as environment changes, so does population (by natural selection) c. Division - over millions of generations, two groups are now so different that they are no longer considered the same

4. “Survival of the Fittest” - only organisms with favorable traits will survive and reproduce. 5. Extinction - species die out completely because they don’t have the resources or adaptations to survive.

The Big Picture ü How do fossils provide evidence that organisms have evolved over time? ü How can organisms be compared to support theory of evolution. ? ü Who is Charles Darwin and his theory of natural selection? ü How are mutations are important to evolution? ü Provide examples of natural selection in action. ü Describe process of speciation.